# Why is $\Delta p \Delta q$ in this diagram infinitely small?

I am curious why the area $\Delta p \Delta q$ is so small that it can safely be neglected.

## 1 Answer

It says "for small values of delta p and delta q". So something small times something small is something very small. Basically we are taking a limit and as delta p and delta q go towards zero, the product goes to zero faster.

• The thing is, we have used this in examples regarding not only marginal, but greater changes, so that's what makes me confused. – faljipx Dec 7 '17 at 23:54