You are Here: Home >< Maths

# C2 differentiation help watch

1. I got the equation down to 3(x-1)(x-1) > 0, the answer in the back of the book is 'x e r =(with a line through it) 1. Does that just mean the answer is anything apart from 1?
2. (Original post by physicshelpme)
I got the equation down to 3(x-1)(x-1) > 0, the answer in the back of the book is 'x e r =(with a line through it) 1. Does that just mean the answer is anything apart from 1?
Yes, because

is positive everywhere apart from at the point where x=1 (it touches the x axis here, and is therefore 0).
3. Thought so, okay the next one has confused me as well.

'Find the values of x for which f(x) is an increasing function, given that f(x) equals:

5x^3 + 12x
I differentiated to get 15x^2 + 12 > 0
3(5x^2 + 4) > 0 and now I don't know what to do
4. have a think about what happens to x if it is squared...
5. (Original post by the bear)
have a think about what happens to x if it is squared...
yea it will always be a positive answer so any value of x will have a result > 0 but how would i write that down as an answer?
6. just say that " for all values of x the derivative is positive... f'(x)>= 12 "

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: March 30, 2013
Today on TSR

### Tuition fees under review

Would you pay less for a humanities degree?

### Can I get A*s if I start studying now?

Discussions on TSR

• Latest
Poll
Useful resources

## Make your revision easier

### 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

Can you help? Study help unanswered threads

## Groups associated with this forum:

View associated groups
Discussions on TSR

• Latest

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