I'm not really sure if you integrated that.

I did this (I wrote it on the back of my notepad):

Is that the right question?

Also what you've written doesn't make 0.4

0.1x(10^2)x4x10+1=401

0.1x0x4+1=1

401-1=400?

What's the part that you've written under the question as well?

You also missed the "dx" after the integral.

I assumed you were just integrating with respect to x.