# Math Help - Calculus Help

1. ## Calculus Help

This question looks really simple and thats whats worrying me a liittle.

Show that if f = f(x, y) and fyy=0, then f(x, y) = g(x)y + h(x) for some funcions g, h.

I simply show that fyy​ = 0 by differnetiation. Is That it ?

2. ## Re: Calculus Help

\displaystyle \begin{align*} f_{yy} &= 0 \\ f_y &= \int{0\,dy} \\ f_y &= g(x) \textrm{ since partial differentiation of a function of x with respect to y gives 0} \\ f &= \int{g(x)\,dy} \\ f &= g(x)\,y + h(x) \end{align*}