Vector........again............?

Question

Find the derivative of the scalar field xy^2+yz at the point P(1,1,2) in the direction of the vector 2x^-y^+2z^

Answer 1

F(x,y,z) = xy^2+yz

F'(x,y,z) = dF/dx +dF/dy +dF/dz

= y^2+ ...... ( i did dF/dx for u, u can do the rest)

then substitute in (1,1,2) into F'

dot product F' with (2x,-y,2z) to get the rate of change in that vectors direction.

do u know how to dot product?