Solving the second for y:
y=x+3
And since any solution will satisfy y=y we can say:
x^2-x-12=x+3 subtract x+3 from both sides
x^2-2x-15=0 now factor
x^2+3x-5x-15-0
x(x+3)-5(x+3)=0
(x+3)(x-5)=0
So there are two solution which occur when x=-3 and 5. Using y=x+3, you can find the corresponding y values...
y(-3)=-3+3=0 and y(5)=5+3=8
So the two solutions are the points (-3,0) and (5,8)
