AQA A Level Maths: Pure复习笔记2.2.4 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

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