# How can i check my solution for Implicit differentiation

I really want to know how can I check if my derivative is correct without using a calculator just to check in the exam

For ex: $x^2 + y^2 = 0$

I know that $\frac{dy}{dx} = -\frac{x}{y}$

But how can I check if it's correct in the exam if harder problems were given?

• $x^2+y^2=0$ is a bad example! It is a single point. – Emilio Novati Jun 9 '17 at 20:42
• In the case that you could solve for $y$ as a function of $x$, you could see whether implicit differentiation and explicit differentiation give the same result. – Foobaz John Jun 9 '17 at 21:34