# Thread: To show that z satisfies the relation

1. ## To show that z satisfies the relation

How to show that the following two equations are related:

2. Originally Posted by totalnewbie
How to show that the following two equations are related:
I am assuming you simply need to verify the second equation given the first?

z = f(x^2 - y^2)

So
zx = f'(x^2 - y^2)*(2x)
zy = f'(x^2 - y^2)*(-2y)

So:
y(zx) + x(zy) =?0

y*f'(x^2 - y^2)*(2x) + x*f'(x^2 - y^2)*(-2y)

= 2xy*f'(x^2 - y^2) - 2xy*f'(x^2 - y^2) = 0 (Check!)

-Dan