WAEC - Mathematics (1997 - No. 7)
Which of the following equations has its roots as 4 and -5?
x2 + 4x - 20 = 0
x2 + x + 20 = 0
x2 - x + 20 = 0
x2 + x - 20 = 0
x2 - x - 20 = 0
Vysvětlení
(x - 4)(x + 5) = 0
x\(^2\) + 5x - 4x - 20 = 0
x\(^2\) + x - 20 = 0
x\(^2\) + 5x - 4x - 20 = 0
x\(^2\) + x - 20 = 0