# Math Help - Equation of a Tangent

1. ## Equation of a Tangent

The tangent to the curve $y = px^3$ at the point A where $x=2$, meets the y-axis at B(0,8). Find the gradient of the curve at point A.

I have attempted using differentiation and found the gradient to be 12p... However, gradient must be in value form..

2. Originally Posted by Punch
The tangent to the curve $y = px^3$ at the point A where $x=2$, meets the y-axis at B(0,8). Find the gradient of the curve at point A.

I have attempted using differentiation and found the gradient to be 12p... However, gradient must be in value form..
hi

At x=2 , y=p(2)^3=8p so the tangent touches the curve at (2,8p)

look closer , $\frac{8p-8}{2}=12p$ , solving this , p=-1/2 so