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C3 Maths help needed

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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.
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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.

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