You are Here: Home >< Maths

integrating 1/2x

Announcements Posted on
Would YOU be put off a uni with a high crime rate? First 50 to have their say get a £5 Amazon voucher! 27-10-2016
1. how come when i integrate it by doing 0.5 x integral of 1/x

i get a different answer to just integrating it without taking the factor of a half,

so for the first one i get 1/2 ln(x)

and for the second one i get 1/2 ln (2x)

(i know when i differentiate both of them, i get the same result, but which is the correct integral?)
2. Both are but the C values will be different.
3. (Original post by cvat)
how come when i integrate it by doing 0.5 x integral of 1/x

i get a different answer to just integrating it without taking the factor of a half,

so for the first one i get 1/2 ln(x)

and for the second one i get 1/2 ln (2x)

(i know when i differentiate both of them, i get the same result, but which is the correct integral?)
They are both correct. The only difference is that in each case, the constant of integration will be different. Obviously this doesn't matter if you're substituting in limits, as the constant cancels out anyway - you'll get the same answer for both.
4. its 1/2 ln x
5. (Original post by cvat)
how come when i integrate it by doing 0.5 x integral of 1/x

i get a different answer to just integrating it without taking the factor of a half,

so for the first one i get 1/2 ln(x)

and for the second one i get 1/2 ln (2x)

(i know when i differentiate both of them, i get the same result, but which is the correct integral?)
As the above poster said, both are correct, but as a general rule, if have an integral I find that you should just leave it as . But that's just me...
6. so if it wasnt a definite integral, and it asked me that question, i'd get the marks for either of them?
7. (Original post by cvat)
so if it wasnt a definite integral, and it asked me that question, i'd get the marks for either of them?
Yes.
8. ok thanks , but yh i think 1/2 ln x + C, does look better too

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: June 11, 2008
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

University open days

Is it worth going? Find out here

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

Chat with other maths applicants