You are Here: Home >< Maths

# Hard integration question watch

1. Attachment 612190612192612200 any help with this question is appreciated... I think the bit but highlighted is what went wrong. Not sure how to solve this...

Thanks
Attached Images

2. better picture .. thanks
3. (Original post by coconut64)
better picture .. thanks
From you should've done IBP with and so I'm not sure what happened on the line right after that, it seems you messed up on the IBP.

P.S. Factor the constants outside the integral, this makes life so much easier.
4. (Original post by RDKGames)
From you should've done IBP with and so I'm not sure what happened on the line right after that, it seems you messed up on the IBP.

P.S. Factor the constants outside the integral, this makes life so much easier.
Is IBP the guess method ? Thanks
5. (Original post by coconut64)
Is IBP the guess method ? Thanks
Integration by parts.
6. (Original post by RDKGames)
Integration by parts.
I did try to do that but the power of u will keep increasing which doesn't really get you anywhere . How does that work ?
7. (Original post by coconut64)
I did try to do that but the power of u will keep increasing which doesn't really get you anywhere . How does that work ?
Yeah that's because you chose for IBP whereas you're supposed to choose which is doable and the integral collapses nicely.
8. (Original post by coconut64)
better picture .. thanks
You got a lot of this question right - so should feel encouraged!

Some tips

When you choose u,if a squareroot is involved you have the option of letting (as here) u^2 = 3x+1 When you integrate, 2u du = 3 dx and so dx = 2/3 du

Taking the constant outside the integral is definitely good advice!

There's a simple rule of thumb worth remembering for integration by parts. It never pays to let u equal e to the power of x because you get stuck in a loop. It always pays to let ln x (log x) equal u because integrating ln x usually then makes progress.

### Related university courses

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: January 17, 2017
Today on TSR

### Exam Jam 2018

Join thousands of students this half term

Poll
Useful resources

### Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here

### How to use LaTex

Writing equations the easy way

### Study habits of A* students

Top tips from students who have already aced their exams