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Solving quadratics and completing the squareEdexcel International A Level Maths: Flashcards

What these 12 flashcards ask

  • What is the zero-product property?
  • State the quadratic formula.
  • First step before factorising or using the formula?
  • Complete the square for x^2+bx+c.
  • Write x^2-10x+7 in completed-square form.
  • State the general completed-square form of ax^2+bx+c.
  • Write 2x^2+12x+5 in completed-square form.
  • Where is the vertex of a(x+p)^2+q?
  • Solve (x-5)^2=18 exactly.
  • Solve 3x^2-7x-6=0.
  • When is completing the square the best method?
  • What do you do with a negative root for a length?

Exam questions on Solving quadratics and completing the square

  1. The function f(x)=x2−10x+7f(x)=x^2-10x+7.
    Hence state the minimum value of f(x)f(x) and the value of xx at which it occurs.2 marks
  2. The function g(x)=2x2+12x+5g(x)=2x^2+12x+5.
    Solve g(x)=0g(x)=0, giving your answers in exact form.2 marks
  3. The function f(x)=3x2−7x−6f(x)=3x^2-7x-6.
    Solve f(x)=0f(x)=0 by factorising.3 marks
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Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).