- #1
Lucy Yeats
- 117
- 0
Homework Statement
Show that f(x,y)=g(x,y)h(x,y) is stationary if and only if:
g=0 and h=0
OR
df/dx=0 and (dg/dx)(dh/dy)=(dg/dy)(dh/dx)
(All the d's in the line above should be curly d's for partial derivatives.)
Homework Equations
The Attempt at a Solution
I tried expressing df as a total derivative then setting this equal to zero, but I wasn't getting anywhere.