Implicit Differentiation Problem, See comments for formula.

Question

anonymous · Answer

$$x ^{2}y=-1 $$ Find the equation of the tangent line that passes through the points (1,-1)

anonymous · Answer

$$2xy+x^2y'=0$$ replace x by 1, y by -1, solve for 
$$y'$$

anonymous · Answer

I am sure I have the differentiation correct, with;

But how do I use this to find the equation of the line?

anonymous · Answer

once you find the slope, use the point-slope formula

anonymous · Answer

Could you refresh my memory on the Point-slope formula?

anonymous · Answer

$$y-y_1=m(x-x_1)$$

anonymous · Answer

So, because I am tasked to find the slope of the tangent line through (1,-1) Would these coordinates be "x1", "y1"? and if so, what would be "y" and "x"?

anonymous · Answer

I am a little confused because of the two variables.

anonymous · Answer

$$x_1=1,y_1=-1$$ m is the slope you need to find from implicit differentiation