Because x is squared, the non-zero integers for x can be either positive or negative, and the result for y will be the same. The resulting graph will be a parabola.
Sample Calculation: ##y=3x^2-7##
If ##x=3##,
##y=3*3^2-7=3*9-7=27-7=20##
##y=20##
If ##x=-3##,
##y=3*-3^2-7=3*9-7=27-7=20##
##y=20##
graph{y=3x^2-7 [-9.88, 10.12, -7.88, 2.12]}