Solving Quadratic Equations (AQA AS Maths): Revision Note

Solving Quadratic Equations

Solving quadratic equations

• We can solve quadratic equations when they are written in the form 

• If given an unusual looking equation, try to rearrange it into this form first

• The three ways to solve a quadratic you must know are

  • Factorising

  • Completing the square

  • Quadratic formula

Solving a quadratic equation by factorising

• Factorising is a great way to solve a quadratic quickly but won't work for all quadratics

• If the numbers are simple, try factorising first

• Once factorised, set each bracket to = 0 and solve

Solving a quadratic equation by completing the square

• Completing the square will work for any quadratic

• Make sure you know how to complete the square

• Remember this will help with questions involving turning points too

  

   

Solving a quadratic equation by the quadratic formula

• The quadratic formula might look complicated but it just uses the coefficients a, b and c from the quadratic equation 

• The quadratic formula will work for any quadratic

Solving a quadratic equation by using a calculator

• Most calculators now have the ability to solve quadratics

• Get used to how your calculator functions work

  

• So the solution to the quadratic equation  are x = 1.5 and x = -4