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I have the funtion f: D --> R which is defined by:

f(x,y) = (2xy)/(x

^{2}+y

^{2}

Im asked to find the equations (in plural) of the tangelnt plane and the normal line to the graph of the function at (1,2)

My attempt:

I use the tangent plane z= f(a,b)+f

_{1}(a,b)*(x-a) + f

_{2}(a,b)*(y-b)

f(1,2) = 4/5

f

_{1}(1,2) = 12/25

f

_{2}(1,2) = -6/25

when I put that into the tangent plane equation and simplify I get: (12/25)x - (6/25)y+4/5

Is this my normal line?

Im very confused, because the assigment asks me to find multiple equations of the tangent plane which I have never done before.

Help is appreciated.