Persamaan kuadrat baru yg akarnya 5 dan -2

x1=5, => x-5=0
x2=-2 => x+2=0

(x-5)(x+2)=0
x²+2x-5x-10=0
x²-3x-10=0

x = 5 maka, x-5 = 0
x = -2 maka, x+2 = -2

Sehingga:
(x-5) (x+2) = 0
x²-5x+2x-10 = 0
x²-3x-10 = 0