x Turn on thread page Beta
 You are Here: Home >< Maths

# C3 Maths help needed watch

1. For Q5 i got to 2x(2x+1)^-2
then differentiated it and subbed in 0.5 but it was incorrect.
Q6 B Just forgotten how to do it
Any help is appreciated.
Attached Images

2. (Original post by GGHarambe)
For Q5 i got to 2x(2x+1)^2
then differentiated it and subbed in 0.5 but it was incorrect.
Q6 B Just forgotten how to do it
Any help is appreciated.
For a, differentiate it, find the gradient at x=6, take the negative reciprocal of it, proceed to construct the equation of the normal.

For b, find the area under the curve from where it crosses the x-axis to point A. Then add on the area of the triangle.

For the last thing, differentiate it and find the solution to dy/dx=0. Plug this into the second differential to determine whether it is a max or a min.
3. (Original post by RDKGames)
For a, differentiate it, find the gradient at x=6, take the negative reciprocal of it, proceed to construct the equation of the normal.

For b, find the area under the curve from where it crosses the x-axis to point A. Then add on the area of the triangle.

For the last thing, differentiate it and find the solution to dy/dx=0. Plug this into the second differential to determine whether it is a max or a min.
Thanks did 6a without trouble and that triangle was the missing part for me on B, thanks.

But the other one im still stuck as when i differentiated it and substituted 1/2 it didn't equal 0.
4. (Original post by GGHarambe)
Thanks did 6a without trouble and that triangle was the missing part for me on B, thanks.

But the other one im still stuck as when i differentiated it and substituted 1/2 it didn't equal 0.
5. (Original post by RDKGames)
-8x(2x+1)^-3
6. (Original post by GGHarambe)
-8x(2x+1)^-3
Nope.

and apply the chain rule.
7. (Original post by RDKGames)
Nope.

and apply the chain rule.
Thanks.

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: September 12, 2016
Today on TSR

### Any tips for freshers...

who are introverts?

### More snow?!

Discussions on TSR

• Latest
Poll
Useful resources

### 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

## 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