If x = 3 and x = -5, then form a quadratic equation? justify answer?

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If x = 3 and x = -5, then form a quadratic equation? justify answer?

2007-02-06 01:22:31 · 3 answers · asked by vmd7878 1 in Science & Mathematics ➔ Mathematics

3 answers

x = 3 , x = - 5

(x - 3)(x + 5) =

x² - 3x + 5x - 15

x² + 2x - 15

The equation is x² + 2x - 15

- - - - - - - - - - -s-

2007-02-06 02:46:29 · answer #1 · answered by SAMUEL D 7 · 0⤊ 0⤋

(x+5)(x-3)

Those values are the "roots" of the quadratic. So reverse the signs and do that to them.

2007-02-06 09:27:55 · answer #2 · answered by l_tu7 2 · 0⤊ 0⤋

(x-3)(x+5) = 0

x^2 +2x -15 = 0

Usually we find the roots from the equation, this time we are just working backwards to find the equation from the roots. :)