General Binomial Expansion (A Level only) (OCR A Level Maths: Pure)

Exam Questions

4 hours43 questions
1
Sme Calculator
2 marks

Find, in ascending powers of x, the binomial expansion of

         open parentheses 1 minus x close parentheses to the power of negative 1 end exponent

up to and including the term in x squared.

Did this page help you?

2a
Sme Calculator
2 marks

Find the first three terms, in ascending powers of x, in the binomial expansion of

        left parenthesis 1 plus x right parenthesis to the power of negative 2 end exponent

2b
Sme Calculator
1 mark

State the values of x for which your expansion in part (a) is valid.

Did this page help you?

3a
Sme Calculator
2 marks

Show that

         square root of 4 minus 4 x end root equals 2 left parenthesis 1 minus x right parenthesis to the power of 1 half end exponent

3b
Sme Calculator
2 marks

Hence find, in ascending powers of x, the first three terms in the binomial expansion of

      square root of 4 minus 4 x end root

3c
Sme Calculator
2 marks

Using x equals 0.02, use your expansion from part (b) to find an approximation to  2 square root of 0.98 end root.

Did this page help you?

4
Sme Calculator
4 marks

Find, in ascending powers of x, the binomial expansion of

        left parenthesis 1 plus 2 x right parenthesis to the power of negative 1 half end exponent

up to and including the term in x cubed.

Did this page help you?

5a
Sme Calculator
4 marks

Find the first three terms, in ascending powers of x, in the binomial expansion of

      left parenthesis 1 minus 1 half x right parenthesis to the power of 1 third end exponent

5b
Sme Calculator
1 mark

State the values of x for which your expansion in part (a) is valid.

 

Did this page help you?

6
Sme Calculator
2 marks

Find the coefficient of the term in x squared in the binomial expansion of

        left parenthesis 1 minus 3 x right parenthesis to the power of negative 3 end exponent

Did this page help you?

7
Sme Calculator
2 marks

The function straight f left parenthesis x right parenthesis is given by

           straight f left parenthesis x right parenthesis equals left parenthesis 1 minus p x right parenthesis to the power of negative 4 end exponent

where p is an integer.

Find the coefficient of the term in x cubed in the binomial expansion of  straight f left parenthesis x right parenthesis, in terms of p.

Did this page help you?

8a
Sme Calculator
3 marks

Given that x is small such that x cubed and higher powers of x can be ignored show that

            left parenthesis 1 minus 1 third x right parenthesis to the power of blank to the power of negative 2 end exponent end exponent almost equal to 1 plus 2 over 3 x plus 1 third x squared

8b
Sme Calculator
2 marks

Using a suitable value of x in the result from part (a), find an approximation for the value of left parenthesis 0.94 right parenthesis to the power of negative 2 end exponent.

Did this page help you?

9
Sme Calculator
5 marks

It is given that

               straight f left parenthesis x right parenthesis equals square root of 1 plus a x end root space space space a n d space space space g left parenthesis x right parenthesis equals cube root of 1 minus a x end root

where a is a non-zero constant.

In their binomial expansions, the coefficient of the x squared term for straight f left parenthesis x right parenthesis is equal to the coefficient of the x term for g left parenthesis x right parenthesis.

Find the value of a.

Did this page help you?

10a
Sme Calculator
3 marks

Show, as partial fractions, that

         fraction numerator 5 minus x over denominator open parentheses 1 plus x close parentheses open parentheses 1 minus x close parentheses end fraction identical to fraction numerator 3 over denominator 1 plus x end fraction plus fraction numerator 2 over denominator 1 minus x end fraction

10b
Sme Calculator
4 marks

Find the first three terms, in ascending powers of x, of the binomial expansion of

(i)
 3 left parenthesis 1 plus x right parenthesis to the power of negative 1 end exponent comma
(ii)
2 left parenthesis 1 minus x right parenthesis to the power of negative 1 end exponent
10c
Sme Calculator
2 marks

Hence show that the first three terms, in ascending powers of x, in the binomial expansion of

            fraction numerator 5 minus x over denominator open parentheses 1 plus x close parentheses open parentheses 1 minus x close parentheses end fraction

are

               5 minus x plus 5 x squared

10d
Sme Calculator
1 mark

Write down the values of x for which this expansion converges.

Did this page help you?

1
Sme Calculator
2 marks

Find, in ascending powers of x, the binomial expansion of

         1 over open parentheses 1 minus x close parentheses squared

up to and including the term in x cubed.

Did this page help you?

2a
Sme Calculator
2 marks

Find the first three terms, in ascending powers of x, in the binomial expansion of

               square root of 1 plus 2 x end root 

2b
Sme Calculator
1 mark

State the values of x for which your expansion in part (a) is valid.

2c
Sme Calculator
1 mark

Using a suitable value of x, use your expansion from part (a) to estimate square root of 1.06 end root, giving your answer to 3 significant figures.

Did this page help you?

3
Sme Calculator
3 marks

Find, in ascending powers of x, the binomial expansion of

            begin mathsize 22px style begin inline style 1 over open parentheses 4 plus 8 x close parentheses squared end style end style

up to and including the term in x cubed.

Did this page help you?

4a
Sme Calculator
3 marks

Use the binomial expansion to show that the first three terms in the expansion of  left parenthesis 1 plus 2 x right parenthesis to the power of negative 3 end exponent are  1 minus 6 x plus 24 x squared.

4b
Sme Calculator
2 marks

Hence, or otherwise, find the expansion of  left parenthesis 1 plus x right parenthesis left parenthesis 1 plus 2 x right parenthesis to the power of negative 3 end exponent up to and including the term in x squared.

Did this page help you?

5a
Sme Calculator
2 marks

The function straight f left parenthesis x right parenthesis is given by

            f left parenthesis x right parenthesis equals square root of 4 minus s x end root

where s is an integer.

(i)
Find the coefficient of the term in x in the binomial expansion of  straight f left parenthesis x right parenthesis, in terms of s.
(ii)
Find the coefficient of the term in x squared in the binomial expansion of  straight f left parenthesis x right parenthesis, in terms of s.

 

5b
Sme Calculator
2 marks

In the binomial expansion of straight f left parenthesis x right parenthesis comma space the coefficient of the term in x is equal to the coefficient of the term in x squared.
Find the value of s.

Did this page help you?

6a
Sme Calculator
3 marks

The functions straight f left parenthesis x right parenthesis and g left parenthesis x right parenthesis are given as follows

         f left parenthesis x right parenthesis equals open parentheses 1 minus 1 half x close parentheses to the power of 1 half end exponent space space space space space space space space g left parenthesis x right parenthesis equals left parenthesis 2 plus x right parenthesis to the power of negative 2 end exponent

(i)
Expand straight f left parenthesis x right parenthesis, in ascending powers of x up to and including the term in x squared.
(ii)
Find the values for x for which the expansion is valid.
6b
Sme Calculator
3 marks
(i)
Expand g left parenthesis x right parenthesis comma in ascending powers of x up to and including the term in x squared.
(ii)
Find the values for x for which the expansion is valid.
6c
Sme Calculator
2 marks
(i)
Find the expansion of fraction numerator square root of 1 minus 1 half x end root over denominator open parentheses 2 plus x close parentheses squared end fraction in ascending powers of x, up to and including the term in x squared.
(ii)
Find the values for x for which the expansion is valid.

Did this page help you?

7
Sme Calculator
3 marks

In the expansion of  open parentheses 1 minus begin inline style 1 fourth end style x close parentheses to the power of n, where n is a negative integer, the coefficient of the term in x squared is begin inline style 3 over 8 end style.

Find the value of n.

Did this page help you?

8a
Sme Calculator
3 marks

Express fraction numerator 2 over denominator open parentheses 1 minus x close parentheses open parentheses 1 plus x close parentheses end fraction  in partial fractions.

8b
Sme Calculator
2 marks

Use the binomial expansion to find the first three terms, in ascending powers of x, in each of  open parentheses 1 minus x close parentheses to the power of negative 1 end exponent and open parentheses 1 plus x close parentheses to the power of negative 1 end exponent

8c
Sme Calculator
2 marks

Hence show that fraction numerator 2 over denominator open parentheses 1 minus x close parentheses open parentheses 1 plus x close parentheses end fraction almost equal to 2 plus 2 x squared

8d
Sme Calculator
1 mark

Write down the values of x for which your expansion in part (c) converges.

Did this page help you?

9a
Sme Calculator
3 marks

Given that x is small such that x cubed and higher powers of x can be ignored show that

        open parentheses 1 minus 1 third x close parentheses to the power of negative 1 end exponent space open parentheses 2 minus x close parentheses to the power of negative 2 end exponent space almost equal to 1 fourth plus 1 third x plus 43 over 144 x squared

9b
Sme Calculator
2 marks

For which values of x is the approximation in part (a) valid?

9c
Sme Calculator
3 marks
(i)
Use your calculator to find the exact fraction of open parentheses 1 minus 1 third x close parentheses to the power of negative 1 end exponent open parentheses 2 minus x close parentheses to the power of negative 2 end exponent  when x equals 0.5
(ii)
Use your calculator to find the fraction from the approximation begin inline style 1 fourth end style plus begin inline style 1 third end style x plus begin inline style 43 over 144 end style x squared when x equals 0.5
(iii)
Find the percentage error in the approximation, giving your answer to two decimal places.

Did this page help you?

10
Sme Calculator
3 marks

 It is given that

            f left parenthesis x right parenthesis equals square root of 9 plus p x end root      and       g left parenthesis x right parenthesis equals fourth root of 16 plus p x end root

                                  

In their binomial expansions, the coefficient of the x squared term for straight f open parentheses x close parentheses is equal to the coefficient of the x term for g left parenthesis x right parenthesis.

Find the value of p.

Did this page help you?

11a
Sme Calculator
2 marks

Express fraction numerator 12 minus x over denominator open parentheses x plus 2 close parentheses open parentheses 3 minus x close parentheses end fraction  in partial fractions.

11b
Sme Calculator
3 marks

Using binomial expansions, up to and including terms in x squared show that
fraction numerator 12 minus x over denominator open parentheses x plus 2 close parentheses open parentheses 3 minus x close parentheses end fraction almost equal to 2 minus 1 half x plus 5 over 12 x squared

11c
Sme Calculator
2 marks

Explain why the approximation in part (b) is only valid for space vertical line x vertical line less than 2.

Did this page help you?

1
Sme Calculator
2 marks

Find, in ascending powers of x, the binomial expansion of

            1 over open parentheses 1 minus 2 x close parentheses cubed

up to and including the term in x cubed.

Did this page help you?

2a
Sme Calculator
3 marks

Use the first three terms, in ascending powers of x in the binomial expansion of

              open parentheses 1 plus 4 x close parentheses to the power of begin inline style 1 third end style end exponent
               

to estimate the value of cube root of 1.2 end root, giving your answer to three significant figures.

2b
Sme Calculator
1 mark

Explain why your approximation in part (a) is valid.

Did this page help you?

3
Sme Calculator
4 marks

Find, in ascending powers of x, the binomial expansion of

         1 over open parentheses 4 plus x close parentheses cubed

up to and including the term in x cubed.

Did this page help you?

4a
Sme Calculator
2 marks

Use the binomial expansion to expand open parentheses 1 minus begin inline style 1 half end style x close parentheses to the power of begin inline style 1 third end style end exponent  up to and including the term in x to the power of 2. end exponent

4b
Sme Calculator
2 marks

Hence, or otherwise, expand  open parentheses 1 minus x close parentheses open parentheses 1 minus 1 half x close parentheses to the power of 1 third end exponent up to and including the term in x squared.

Did this page help you?

5
Sme Calculator
3 marks

In the expansion of  1 over open parentheses 3 plus p x close parentheses cubed  the coefficient of the term in x squared is double the coefficient of the term in x cubed.  Find the value of  p.

Did this page help you?

6a
Sme Calculator
2 marks

The functions straight f left parenthesis x right parenthesis and  straight g left parenthesis x right parenthesis are given as follows

               straight f left parenthesis x right parenthesis equals open parentheses 4 plus 3 x close parentheses to the power of 1 half end exponent space space space space space space space space space space space space space space space space space straight g left parenthesis x right parenthesis equals open parentheses 9 minus 2 x close parentheses to the power of negative 1 half end exponent

Expand straight f left parenthesis x right parenthesis, in ascending powers of x up to and including the term in x squared.

6b
Sme Calculator
2 marks

Expand straight g open parentheses x close parentheses, in ascending powers of x up to and including the term in x squared.

6c
Sme Calculator
2 marks

Find the expansion of square root of fraction numerator 4 plus 3 x over denominator 9 minus 2 x end fraction end root  in ascending powers of x, up to and including the term in x squared.

6d
Sme Calculator
2 marks

Find the values of x for which your expansion in part (c) is valid.

Did this page help you?

7
Sme Calculator
3 marks

In the expansion of  begin mathsize 20px style open parentheses 1 minus begin inline style 4 over 3 end style x close parentheses to the power of n end style , where n is a real number, the coefficient of the term in x squared is begin mathsize 20px style begin inline style negative 16 over 81 end style end style.

Find the possible values of n.

Did this page help you?

8a
Sme Calculator
3 marks

Express fraction numerator 4 plus 5 x minus x squared over denominator open parentheses 1 minus x close parentheses open parentheses 1 plus x close parentheses squared end fraction  in partial fractions.

8b
Sme Calculator
3 marks

Use the binomial expansion to find the first three terms, in ascending powers of x, in each of open parentheses 1 minus x close parentheses to the power of negative 1 end exponent, open parentheses 1 plus x close parentheses to the power of negative 1 end exponent, and open parentheses 1 plus x close parentheses to the power of negative 2 end exponent.

8c
Sme Calculator
2 marks

Hence express  fraction numerator 4 plus 5 x minus x squared over denominator open parentheses 1 minus x close parentheses open parentheses 1 plus x close parentheses squared end fraction as the first three terms of a binomial expansion in ascending powers of  x.

8d
Sme Calculator
1 mark

Write down the values of x for which your expansion in part (c) converges.

Did this page help you?

9a
Sme Calculator
3 marks

Given that x is small such that x cubed and higher powers of x can be ignored show that

         left parenthesis 2 plus 3 x right parenthesis to the power of negative 1 end exponent left parenthesis 3 minus 2 x right parenthesis to the power of negative 2 end exponent almost equal to 1 over 18 minus 1 over 108 x plus 19 over 216 x squared

9b
Sme Calculator
3 marks

Find the percentage error between your calculator answer and the approximation in part (a) when x equals 0.1, giving your answer to one decimal place.

9c
Sme Calculator
2 marks

For which values of x is the approximation in part (a) valid?

Did this page help you?

10a
Sme Calculator
3 marks

In the binomial expansion of  square root of 4 plus begin inline style p over q end style x end root   where p less than 0 less than q, the coefficient of the x squared term is equal to the coefficient of the x cubed term.

Show that space p equals negative 8 q.

10b
Sme Calculator
2 marks

Given further that p q equals negative 8 space find the values of p and q.

Did this page help you?

11a
Sme Calculator
3 marks

Express fraction numerator 1 minus 7 x over denominator open parentheses x plus 2 close parentheses open parentheses 3 minus x close parentheses end fraction  in the form  fraction numerator A over denominator x plus 2 end fraction plus fraction numerator B over denominator 3 minus x end fraction, where A and B are integers to be found.

11b
Sme Calculator
3 marks

Hence, or otherwise, find the binomial expansion of fraction numerator 1 minus 7 x over denominator open parentheses x plus 2 close parentheses open parentheses 3 minus x close parentheses end fraction, in ascending powers of x, up to and including the term in x squared.

11c
Sme Calculator
2 marks

The expansion in part (b) is to be used to approximate the value of a fraction.

(i)
If x equals 0.1, which fraction is being approximated?
(ii)
Which fraction does the approximation give?

Did this page help you?

1
Sme Calculator
2 marks

Find, in ascending powers of x, the binomial expansion of

         1 over open parentheses 1 minus 1 third x close parentheses to the power of 4

up to and including the term in x cubed.

Did this page help you?

2a
Sme Calculator
3 marks

Use the first three terms, in ascending powers of x, in the binomial expansion of

         fraction numerator 1 over denominator square root of 1 minus 1 half x end root end fraction

to estimate the value of fraction numerator 1 over denominator square root of 0.95 end root end fraction, giving your answer to two decimal places.

2b
Sme Calculator
1 mark

Explain why you would not be able to use your expansion to approximate fraction numerator 1 over denominator square root of 3 end fraction.

Did this page help you?

3
Sme Calculator
3 marks

Find, in ascending powers of x, the binomial expansion of

         1 over open parentheses 3 minus 2 x close parentheses to the power of 4

up to and including the term in x cubed.

Did this page help you?

4
Sme Calculator
4 marks

Expand left parenthesis 1 minus 1 half x right parenthesis left parenthesis 9 plus 3 x right parenthesis to the power of negative 1 half end exponent up to and including the term in x squared.

Did this page help you?

5
Sme Calculator
4 marks

In the expansion of   1 over open parentheses 8 plus 2 q x close parentheses to the power of 1 third end exponent,  the coefficient of the term in x squared is one-seventh of the coefficient of the term in x cubed.  Find the value of q.

Did this page help you?

6
Sme Calculator
5 marks

The functions straight f open parentheses x close parentheses and straight g open parentheses x close parentheses are given as follows

               straight f left parenthesis x right parenthesis equals 8 minus x space space space space space space space space space space space space space space straight g left parenthesis x right parenthesis equals 8 plus 2 x     

Find the binomial expansion of   begin mathsize 20px style cube root of begin inline style fraction numerator straight f open parentheses x close parentheses over denominator straight g open parentheses x close parentheses end fraction end style end root end style, in ascending powers of x, up to and including the term in x squared.  Also find the values of x for which your expansion is valid.

Did this page help you?

7
Sme Calculator
4 marks

In the expansion of  open parentheses 16 minus 2 x close parentheses to the power of n, where n is a real number, the coefficient of the term in x squared is 16 to the power of n cross times 5 over 2048.

Given that vertical line n vertical line less than 1 find the value of n.

Did this page help you?

8a
Sme Calculator
3 marks

Express  fraction numerator 2 open parentheses 2 minus 5 x plus x squared close parentheses over denominator open parentheses x plus 2 close parentheses open parentheses 2 minus x close parentheses squared end fraction  in partial fractions.

8b
Sme Calculator
5 marks

Express fraction numerator 2 open parentheses 2 minus 5 x plus x squared close parentheses over denominator open parentheses x plus 2 close parentheses open parentheses 2 minus x close parentheses squared end fraction  as the first three terms of a binomial expansion in ascending powers of x.

8c
Sme Calculator
1 mark

Write down the values of x for which your expansion in part (b) converges.

Did this page help you?

9a
Sme Calculator
4 marks

Given that x is small such that x cubed and higher powers of x can be ignored show that

         left parenthesis 4 minus 3 x right parenthesis to the power of negative 2 end exponent left parenthesis 2 minus x right parenthesis to the power of negative 3 end exponent almost equal to 1 over 128 plus 3 over 128 x plus 87 over 2048 x squared

9b
Sme Calculator
3 marks

Find the percentage error between your calculator answer and the approximation in part (a) when x equals 0.2, giving your answer to one decimal place.

9c
Sme Calculator
2 marks

For which values of x is the approximation in part (a) valid?

Did this page help you?

10
Sme Calculator
4 marks

It is given that

         straight f left parenthesis x right parenthesis equals square root of 4 plus a x end root        and              straight g left parenthesis x right parenthesis equals fourth root of 16 plus b x end root

The binomial expansions of  straight f left parenthesis x right parenthesis  and  straight g left parenthesis x right parenthesis have the following properties:

(i)
The coefficient of the x cubed term in the expansion of straight f open parentheses x close parentheses is 72 times larger than the coefficient of the x squared term in the expansion of straight g open parentheses x close parentheses.

(ii)

The coefficient of the x term in the expansion of straight f open parentheses x close parentheses is 24 times larger than the coefficient of the x term in the expansion of straight g open parentheses x close parentheses.

 

Find the values of a and b.

Did this page help you?

11a
Sme Calculator
5 marks

Find the binomial expansion of fraction numerator 15 over denominator open parentheses x minus 4 close parentheses open parentheses 5 x minus 2 close parentheses to the power of apostrophe end fraction, in ascending powers of x, up to and including the term in x squared.

11b
Sme Calculator
2 marks

Explain why the expansion found in part (a) cannot be used when x equals 0.6.

Did this page help you?