Hey there! Sign in to join this conversationNew here? Join for free
 You are Here: Home >< Maths

# C3 Help. Watch

1. Hey,

How would I show that the differentiation of:-

1 - (2)/(3x^2+2) with a domain of (0,infinite) is always positive? When I differentiate it I get - (12x)/(3X^2+2)^2. Or have I differentiated it wrong? Any help please? Thank you.
2. I can't see what you've written. Too many brackets. Also the use of - doesn't help especially in the first instance. I can hazard a guess though.
3. (Original post by StephenP91)
I can't see what you've written. Too many brackets. Also the use of - doesn't help especially in the first instance. I can hazard a guess though.
Sorry, the - is minus sign. I can't use latex .
4. (Original post by FutureMedic)
Sorry, the - is minus sign. I can't use latex .
That's not my problem. The first line. 1-(2). Are you saying 1-2 or is it question 1? and then it says -(2) ?

If it is minus 2, you end up with:

Then you can just simply say is always a positive value for x belonging to the positive real numbers and since the domain is only the positive reals then this is fine. is postive regardless of whether or not x is negative or positive. Then just conclude saying that a positive value divided by a positive value is always positive.
5. Differentiate again to find d2y/dx2
6. (Original post by StephenP91)
That's not my problem. The first line. 1-(2). Are you saying 1-2 or is it question 1? and then it says -(2) ?

If it is minus 2, you end up with:

Then you can just simply say is always a postively value for x belonging to the positive real numbers. is postive regardless of whether or not x is negative or positive. Then just conclude saying that a positive value divided by a positive value is always positive.
Hi,

It's 1 minus the fraction numerator (2), denominator (3x^2+2).
7. (Original post by FutureMedic)
Hi,

It's 1 minus the fraction numerator (2), denominator (3x^2+2)^2.
Alrighty then. Just read what I said in the previous post.
8. (Original post by StephenP91)
Alrighty then. Just read what I said in the previous post.
Thank you.
9. (Original post by StephenP91)
Alrighty then. Just read what I said in the previous post.
Isn't there a minus when it's differentiated though coming from the ^-1?
10. (Original post by FutureMedic)
Isn't there a minus when it's differentiated though coming from the ^-1?

The minus 1 you bring up is made plus by your -2.

Differentiate that.

Then when you multiply that by the -2, you get what I previously said.

Reply
Submit reply
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: December 7, 2010
Today on TSR

### What is the latest you've left an assignment

And actually passed?

### Simply having a wonderful Christmas time...

Discussions on TSR

• Latest
• ## See more of what you like on The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

• 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
• ## See more of what you like on The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

• 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.