Mathematics for IGCSE & O level - Graphs Of Functions (Section 2 - No. 41)

The graph of y=x²+2x-8 crosses the x axis at:

x=-4

x=2

y=-8

y=0

To find x-intercepts you set y=0. Factoring, we get (x+4)(x-2)=0 thus, x=-4 and x=2.