Can someone help me with any of these problems? I'll really appreciate it!

12) Complete the curve defined by x^4+4x^2y+y^4=1 find dy/dx

13) For the curve (x+1)/(y+1)=2 dy/dx= [(y+1)(2y+1)]/(x+1)

a) if dy/dx= [(y+1)(2y+1)]/(x+1) Find the equation of the tangent line to the curve at (3,1)

b) if dy/dx= [(y+1)(2y+1)]/(x+1) write the equation(s)of any horizontal or vertical tangent line(s) OR show work to explain why there are none

14) if dy/dx= x^2y^2 find d^2y/dx^2 as an expression of x and y only.You do not need to simplify.