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    Sample 6 Paper 1 Question 13 shanekenna

    Can't work this one out. Can anyone help?

    axsquared + bx + c = 0 is the general form of a quadratic equation. Find the values of a, b, c if the equation has roots x=2/3 and x=-1/2?

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      Basically you need to find a quadratic with those roots.


      x = 2/3

      3x = 2

      (3x-2) = 0

      Do similarly for x = -1/2

      You get (2x+1) = 0

      (3x-2) and (2x+1) are factors of the quadratic.

      So multiply them together and you will get something in the form of axsquared + bx + c = 0

      By comparing what you get with axsquared + bx + c = 0, you can say what a, b and c are.

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