1.x^2+3xy+y^2=15 And the answer says -y^2/x^2

2.(1/x)+(1/y) the answer says -y^2/x^2.

For 1., dy/dx(x^2+3xy+y^2)=dy/dx(15)->(2x+3x+3y(dy/dx)+2y(dy/dx)=0 (for 3xy, I used the product rule for x and y and got x+y and plugged it to 3 to get this function.) What am i doing wrong with this equation?

With 2. I used the quotient rule, and got (x/x^2)+(y/y^2) and I know I am wrong on this one from the start. please help.