I believe you want to find the volume of the solid generated by rotating these two curves about the x-axis.
The curve y=x^2 and the line y=8x meet in two points. the origin(0,0) and the point (8,64).
if you graph these two curves you will find the intersection point (8,64)
to find the volume of the solid that is formed by the curve y=x^2 and the line y=8x you must get the definite integral from 0 to 8 of the function (8x)^2-x^4
and multiply the final result with π .
try it it is easy.