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- Homework Statement
- Find the straight tangent line at (2,-1) to the level curve of f(x,y)=x^2-y^2

- Relevant Equations
- f(x,y)=x^2-y^2

Point: (2,-1)

I have solved the gradient:

gradf(2,-1)=(4,2)

and have the tangent plane:

4x+2y+3=0

Somehow the answer is:

3=2x+y

And i really don´t understand why.

gradf(2,-1)=(4,2)

and have the tangent plane:

4x+2y+3=0

Somehow the answer is:

3=2x+y

And i really don´t understand why.