Thread: Please Help Calculus

1. Please Help Calculus

Please help.

Prove that for any differentiable function z=f(x,y), the steepest ascent of z at the point is given by

2. Are you familiar with directional derivatives? It may be proven that

$D_{\mathbf{u}}f(x,y)=\nabla f(x,y)\cdot\mathbf{u}$

for a unit vector $\mathbf{u}$.