# Thread: Area Between 2 Graphs (integration)

1. ## Area Between 2 Graphs (integration)

The shaded area is the area needed. I can't seem to get the same answer as the book.

I think the problem is I am not integrating the 'root' 2x correctly.

Can someone tell how to integrate this?

Thanks

(PS. Answer = 2 )

2. Originally Posted by r_maths

The shaded area is the area needed. I can't seem to get the same answer as the book.

I think the problem is I am not integrating the 'root' 2x correctly.

Can someone tell how to integrate this?

Thanks

(PS. Answer = 2 )
here

3. Originally Posted by r_maths

I think the problem is I am not integrating the 'root' 2x correctly.
you did in fact integrate this incorrectly. you need to use substitution to do this (that is the standard way--from experience you would know that the integral is half of the answer you got). the way i did it, i didn't have to integrate that. if you're still not sure about how to integrate something like this, say so

4. Here's some good stuff to know

5. Thanks alot!

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I've another question though.

I worked out where the graphs intersects.
0.25^2 - 3x + 8 = 0
x = 4 or x = 8
However, how is it possible to know which is the correct one?
The answer is 26 and 2/3 (26.666...) so x = 4.
The only way I knew it was 4 is because I looked at the answer, but obviously in the exams
I will not have the answers to check at. Thanks

EDIT: Last question, I only worked out half of the graph and times answer by 2, is this ok?