find the gradient of f(x,y)=7*x^5*y^2-9*x^8*y^6
Evaluate the gradient of f at the point P, where
f(x,y,z)=x^4*y^3*z, P(-1,3,-1)
Ok. So the gradient is just a vector field of the partial derivatives. For #1) grad F = (df/dx , df/dy). And those are partial derivatives of course.
#2) grad F = (df/dx, df/dy, df/dx) and once you get your vector field plug in the particular case of point (-1,3,1) that they want.