# Math Help - Integrals

1. ## Integrals

I have an idea of the concept this problem is trying to ask but I can't quite figure out how to solve it.

Given that:
integral from 0 to 3 f(x) dx= integral from 0 to 1 f(x) dx + integral from 2 to 1 f(x)dx + integral from 2 to 3 f(x)dx

Find integral from 1 to 2 f(x)dx

I don't really know how to think of it. I know an integral equals area under the curve but can't really see what else i'm missing.

2. Originally Posted by swimmergirl
I have an idea of the concept this problem is trying to ask but I can't quite figure out how to solve it.

Given that:
integral from 0 to 3 f(x) dx= integral from 0 to 1 f(x) dx + integral from 2 to 1 f(x)dx + integral from 2 to 3 f(x)dx
are you sure that shouldn't be 1 to 2? maybe not.

Find integral from 1 to 2 f(x)dx
Hint: $\int_1^2 f(x)~dx = - \int_2^1 f(x)~dx$

3. no original problem is correct. I still can't figure it out.

4. Originally Posted by swimmergirl
no original problem is correct. I still can't figure it out.
really? what have you tried since you saw my hint?

5. Hi swimmer girl:
integral from 0 to 3 f(x) dx= integral from 0 to 1 f(x) dx + integral from 2 to 1 f(x)dx + integral from 2 to 3 f(x)dx

Find integral from 1 to 2 f(x)dx

the previous post should have given u a clue on how to solve this:

0 to 3 f(x)dx - 0 to 1 f(x)dx - 2 to 3 f(x)dx = integral from 2 to 1 f(x)dx

so the integral from 1 to 2 f(x)dx = -(left hand side of previous equation)

This should clear things up. I'm new to this forum so im not sure how to use the equation editor.