You are Here: Home >< Maths

# integration help(i think?)

Announcements Posted on
TSR's new app is coming! Sign up here to try it first >> 17-10-2016
1. 1. The gradient of a curve is given by dy/dx=3x-4. Find the equation of the curve given that it passes through the point (3,1)

so integrate 3x-4 so= 3x^2/2-4x. can i get rid of the 2 on the denominator?
2. (Original post by dongonaeatu)
1. The gradient of a curve is given by dy/dx=3x-4. Find the equation of the curve given that it passes through the point (3,1)

so integrate 3x-4 so= 3x^3/3-4x. can i get rid of the 3 on the denominator?
Where are you getting the 3 from?
3. To integrate you increase the power by one and divide by the new power. So yes you can cancel the 3 and would therefore have y=x^3-4x+d

Don't forget to include the constant!!!!

Solve using the values you know to find d.
4. Is your original expression supposed to be dy/dx = 3x - 4, i.e. the equationn of a straight line? If you've integrated incorrectly.

If it is supposed to be dy/dx = 3x^2 - 4, i.e. a quadratic, then yes, this gives you y = (3x^3)/3 - 4x + c. Of course you can cancel the 3s in the first term - it is just three times something divided by three.
5. Isn't it divided by two, not three :P

You divide by the new power bro

Also, +k on the end.
6. (Original post by CD315)
Where are you getting the 3 from?
sorry, i meant 2.

is the final answer for the equation of the curve y=3x^2/2-4x-1/2
7. (Original post by tamimi)
Isn't it divided by two, not three :P

You divide by the new power bro

Also, +k on the end.
is the final answer for the equation of the curve y=3x^2/2-4x-1/2
8. That's what I make it.
9. (Original post by dongonaeatu)
is the final answer for the equation of the curve y=3x^2/2-4x-1/2
I believe it is Either that or we're both wrong.
10. Yep I seem to get -1/2. You don't need to get rid of the two, just sub in your x and y values after you've integrated. Best way just in case you make a mistake in getting rid of the 2.
11. (Original post by mr tim)
Yep I seem to get -1/2. You don't need to get rid of the two, just sub in your x and y values after you've integrated. Best way just in case you make a mistake in getting rid of the 2.
thanks tim, are you good at trigonometry?
12. (Original post by dongonaeatu)
thanks tim, are you good at trigonometry?
if you can tell me the question then I'll or someone else will tell you how to answer it.
13. (Original post by mr tim)
if you can tell me the question then I'll or someone else will tell you how to answer it.
http://www.thestudentroom.co.uk/show...260&p=37114590

## Register

Thanks for posting! You just need to create an account in order to submit the post
1. this can't be left blank
2. this can't be left blank
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
1. Oops, you need to agree to our Ts&Cs to register

Updated: April 12, 2012
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

### 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