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Exponents (DP IB Maths: AI HL)
Revision Note
Laws of Indices
What are the laws of indices?
- Laws of indices (or index laws) allow you to simplify and manipulate expressions involving exponents
- An exponent is a power that a number (called the base) is raised to
- Laws of indices can be used when the numbers are written with the same base
- The index laws you need to know are:
- These laws are not in the formula booklet so you must remember them
How are laws of indices used?
- You will need to be able to carry out multiple calculations with the laws of indices
- Take your time and apply each law individually
- Work with numbers first and then with algebra
- Index laws only work with terms that have the same base, make sure you change the base of the term before using any of the index laws
- Changing the base means rewriting the number as an exponent with the base you need
- For example,
- Using the above can them help with problems like
Examiner Tip
- Index laws are rarely a question on their own in the exam but are often needed to help you solve other problems, especially when working with logarithms or polynomials
- Look out for times when the laws of indices can be applied to help you solve a problem algebraically
Worked example
Simplify the following equations:
i)
.
ii)
.
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