Hey! Sign in to get help with your study questionsNew here? Join for free to post
 You are Here: Home >< Maths

# Maths C3 help please - integrating exponentials

Announcements Posted on
Why bother with a post grad course - waste of time? 17-10-2016
1. The diagram shows sketches of the graphs y=2-e^-x and y=x. These graphs intersect at x=a where a>0.
Use integration to show that the area (between 0 and a and the two lines) is equal to 1+ a - 1/2a^2.

I can integrate and get 2x + e^-x - 1/2x^2 but I can't get the answer
2. (Original post by Jasminea)
The diagram shows sketches of the graphs y=2-e^-x and y=x. These graphs intersect at x=a where a>0.
Use integration to show that the area (between 0 and a and the two lines) is equal to 1+ a - 1/2a^2.

I can integrate and get 2x + e^-x - 1/2x^2 but I can't get the answer
So now plug in a into the expression you have, you'll get an answer out in terms of a.

Now plug in 0 into the expression you have. Subtract this from your previous answer.
3. I tried that but it doesn't work. I got 2a +e^-a - 1/2a^2 - 1
4. do you know how else to do it?
5. (Original post by Jasminea)
I tried that but it doesn't work. I got 2a +e^-a - 1/2a^2 - 1
Which is the correct answer for the area between the two graphs. Post a picture of the question, please.
6. But the answer is
1+ a - 1/2a^2.
as said above
7. Question 12
8. (Original post by Jasminea)
Question 12
Sure. You have , but you also know that , so: , substitute this into your expression for the area.
9. Thanks a lot! My friend and I were getting quite stuck.
10. (Original post by Jasminea)
Thanks a lot! My friend and I were getting quite stuck.
If you click on the quotation marks below a post, it lets you quote people so that they know you've replied, just like how you know he's replied. Otherwise they have no clue if you've replied or not (which is why you had to post twice at one stage).

Write a reply…

Submit reply

## Register

Thanks for posting! You just need to create an account in order to submit the post
1. this can't be left blank
that username has been taken, please choose another Forgotten your password?
2. this can't be left blank
this email is already registered. Forgotten your password?
3. this can't be left blank

6 characters or longer with both numbers and letters is safer

4. this can't be left empty
your full birthday is required
1. Oops, you need to agree to our Ts&Cs to register
2. Slide to join now Processing…

Updated: July 4, 2016
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:
Today on TSR

### How does exam reform affect you?

From GCSE to A level, it's all changing

Poll
Useful resources

## Make your revision easier

### Maths Forum posting guidelines

Not sure where to post? Read here first

### How to use LaTex

Writing equations the easy way

### Study habits of A* students

Top tips from students who have already aced their exams

Can you help? Study help unanswered threads

## Groups associated with this forum:

View associated groups
Study resources

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.