A) Computer the tangent line to the curve x^4-yx^2+y^4 =1 at the point (-1,1)

Ok so I did the derivative =

4x^3-2x y' + 4x^3 y' = 0

Do I just take the point x (-1) put it in the formula for X to find y' and that's it? :S

B) Iterate Newton's method 2 times to produce a rational number approximating 4^-3. Use 2 as your initial guess.

Xn+1 = Xn - f(Xn)/(f'(Xn))

so... I'm lost about there :/