Multivariable question!
Find the equation of the plane tangent to the graph of the function
z(x,y)=2x^2-7y^2-x-6y+3 at the point (x,y)=(5,-1).

I say that plane z = 19x+8y-87, but it's supposedly incorrect, help?

Question

Multivariable question! 
Find the equation of the plane tangent to the graph of the function
z(x,y)=2x^2-7y^2-x-6y+3 at the point (x,y)=(5,-1).

I say that plane z = 19x+8y-87, but it's supposedly incorrect, help?

loser66 · Answer

Let see: $f'_x= 4x-1$ hence at (5, -1) , $f'_x= 19$
             $f'_y= -14y -6$, at (5,-1), $f'_y=  8$
hence, the tangent line equation is $Z= 19(x-5) +8(y+1) = 19x-95+8y+8=19x+8y-87$

loser66 · Answer

Hence, we are the same boat. hehehe

sh3lsh · Answer

Haha, oh well. 
Thanks for confirming it!