hi, my question is: find the equations of the tangents to the curve with equation

at the points P(-1, 0) and Q(5, 0). prove that these two tangents intersect at the point (2, 18)

the first thing i did was expand the brackets and differentiate with x = -1 (for P). which resulted in:

so then

and usig x = -1 the gradient comes to 6

so the equation is

so for Q i did the same thing. used x = 5 for

which gave a gradient of - 6

so the equation is

how would i prove these two tangents intersect at point (2, 18)?

thanks, mark