i have a problem where I have to find tangent line to the curve: 1x2–4xy+4y3=81
At the point (–71).
Can anyone help?
Differentiate both sides with rspect to x:
Use the product rule on 4xy to get $\displaystyle 4y + 4x \frac{dy}{dx}$.
Use the chain rule on $\displaystyle 4 y^3$ to get $\displaystyle 12 y^2 \frac{dy}{dx}$.
Now substitute (-7, 1) and make $\displaystyle \frac{dy}{dx}$ the subject.