One x intercept for a parabola is at the point (1,0). use the factor method to find the other x intercept for the parabola defined by y=5x^2+5x-10

Hello : 
let : f(x) =5x²+5x-10
f(1) = 0
f(x) divisible by (x-1)
f(x) = (x-1)g(x)
g(x) =ax+b
f(x) = (x-1)(ax+b)
    5x²+5x-10  = ax²+bx-ax-b= ax²+(b-a)x-b
   a=5 and : b-a =5 and : -b =-10b=10
f(x) =(x-1)(5x+10)
f(x) = 0 : x-1 =0 and :5x+10 =0
x= 1 and x=-2

the other x intercept for the parabola is : -2