Question

Compute the linear approximation of f(x, y)=sqrt(x^2+y^2) at (3, 0).

Fx=x^4 fy=y^4
fx(3, 0)=81 fy(3, 0)=81
f(3, 0)=3
L(x, y)=3+81(x-3)-(y-0)
=3+81x-243-y=-246+81x-y
But the answer I got is wrong.

Answer 1

Please try the partial derivatives again.

Practice, if \(h(x) = \sqrt{x^{2} + 1}\), find h'(x)