The question gives the point of intersection and asks to show that these are points of intersection so I don't know if they just want us to substitute into both equations to check Left and right side are equal or whether they want us to solve it simultaneously
Or you could solve one by solving for the other, (by this method i got -1)
and you could use the given points and sub it in to prove they really do intersect at x= -1 and x=0