Sophee

Let y = f(x) be the continuous function that satisfies the equation x^4 - (5x^2)(y^2) + 4y^4 = 0 and whose graph contains the points (2,1) and (2,2). Let L be the line tangent to the graph of f at x = 2. (a) Find and expression for y'. (b) Write an equati...

I think a0 is (-4x^3+10xy^2)/(-10x^2y+16y^3) and that makes b y=1/2x. However, I can't seem to get anything for c nor d. How do I start?

The answer is 34.