My initial thought was that it's surprising that the engineer is using i whereas the mathematician is using j. But I know some engineers who are hardcore in favour of i. No mathematicians who prefer j though. So if such an engineer were dating a mathematician of all people who used j, I could see that being ♠ .

Hum... I don't think the integral "operator" applies by multiplication.

You can put the dx at the beginning of the integral, but not before it.

Gods I wish I had a top to troll like this

Physicist behavior

But physicists actually do that? They often write it like this: ∫ dx f(x) or this: ∫∫∫ dxdydz f(x,y,z)