Integrating 2(100+t) A friend and I were doing some math together when we had to integrate $2(100 + t)$.
I just multiplied it out and integrated $200 + 2t$, which should be $200t + t^2$.
He did u-substitution and got $(100 + t)^2$.
When I take the derivative of both of ours, I seem to get the same thing. But $(100 + t)^2 = 10000 + 200t + t^2$, which is not equal to just $200t + t^2$.
What is going on here?

When you integrate indefinitely, you must add an arbitrary constant. So in essence, your answers are the same, up to addition of a constant (10,000 in this case). In other words, his constant will be 10,000 less than yours.
