# Verify a function is a solution.

#### ISITIEIW

##### New member
Verify that x^2 + y^2 = cy is a solution of dy/dx = (2xy)/(x^2-y^2) where c is a constant.

I don't know how i should start this problem. Ive done a couple DE questions but nothing like this.. Thanks

#### Ackbach

##### Indicium Physicus
Staff member
One trick I learned (from Jester) when doing these problems is to eliminate the constant $c$, whenever possible, for first-order. To do that, simply solve for the constant and then take the necessary derivative. Your goal here is to plug the function and its derivative into the DE and show that you get equality.