Originally Posted by

**jllinas** Ive been trying to figure out this problem for a while now... I can solve it graphically but I am trying to solve it algebraically using the derivative but I am still stuck:

On the curve y=x^3, find two points, P and Q, for which the tangent line at P crosses Q. Furthermore, the slope of the tangent line at Q is 4 times the slope of the tangent line at P.

I got this far then I hit a roadblock:

q = 2p.... the two tangent lines:

3p^2(x-p) + p^3 = 12p^2(x-2p) + 8p^3

Thanks in advance!