Why don't I have to put the +C after my answer for a definite integral?
When you evaluate a definite integral, we can think about using the "+C" and see what happens. Let's take (INT)2x dx between 2 and 3. We then have [x2+C] between 2 and 3. For x=3 we have 9+C, and for x=2 we have 4+C. To evaluate the integral we subtract the lower limit from the upper one so we have (INT)2x dx = (9+C) - (4+C) =9+C-4-C =5. So generally, we can say that when we evaluate a definite integral, the constant terms cancel out so we don't usually bother to write them down.
JC
Related Maths A Level answers
All answers ▸Find the tangent to y = x^2 - 4x + 9 at the point (3,15)
What's the point of writing my mathematics well if I don't get extra marks for it?
Find dy/dx for y=5x^3−2x^2+7x−15
Use integration by parts to find ∫ (x^2)sin(x) dx. (A good example of having to use the by parts formula twice.)