WAEC - Mathematics (1988 - No. 19)
Find the quadratic equation whose roots are x = -2 or x = 7
x2 + 2x - 7 = 0
x2 - 2x + 7 = 0
x2 + 5 +14 = 0
x2 - 5x - 14 = 0
x2 + 5x - 14 = 0
Explicació
x + 2 and x - 7 are factors
(x+2)(x+7) = 0
x(x-7) + 2(x-7) = 0
x2 - 7x + 2x - 14 = 0
x2 - 5x - 14 = 0
(x+2)(x+7) = 0
x(x-7) + 2(x-7) = 0
x2 - 7x + 2x - 14 = 0
x2 - 5x - 14 = 0