x^2+x-30 = 0
(x+6)(x-5) = 0
The roots of this equation are (x+6) = 0.......==> x1 = -6
and (x-5) = 0..............==> x2 = 5.................
These values of X correspond to the arguments of the function
f(x) = x^2+x-30 , Which make f(x) = 0
So we are basically finding the points that intersect the graph on the X Axis
