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# more! Product rule differntiaion C3 watch

1. i used the chain rule and then the product rule to get:

But it doesn't seem to work! is that bit above wrong?

if its hard to read, its to the power of 0.5
2. Is the question ?
3. (2x)(2x+1)^-0.5 + 2(2x+1)^0.5
4. give me a sec to write it.

edit - cksuper has got it
5. root(2x + 1) differentiates to 2(1/2)(2x + 1)^(-1/2) = (2x + 1)^(-1/2). Did you get that? Where are those threes coming from?
6. I get that both the 3s should be replaced by 2s.
7. just let the first part = u, the second = v
Then carry out: uv' +vu'
8. (Original post by CKsuper1)
(2)(2x)(2x+1)^-0.5 + 2(2x+1)^0.5

why isn't it (2)(1/2)(2x)(2x + 1)^-0.5 + 2(2x + 1)^0.5?
9. because you square the differential which is 2 then factorise- or alternatively you can expand the bracket then simplify
10. yh...soz, just editted it...my mistake
11. (Original post by CKsuper1)
(2x)(2x+1)^-0.5 + 2(2x+1)^0.5
ok, how did i get the instead of the ?

the question is
12. argh, my fault, i wrote the question wrong!
13. becuase
root(2x + 1) differentiates to 2(1/2)(2x + 1)^(-1/2) = (2x + 1)^(-1/2).
14. (Original post by DreamsComeTrue.)
ok, how did i get the instead of the ?

the question is
Ur Q above says 2x(2x + 1)^0.5....

If it was 3x: 3x(2x+1)^-0.5 + 3(2x+1)^0.5
15. (Original post by shyamp)
give me a sec to write it.

edit - cksuper has got it
hehe....soz
16. omg, i just subed x = 4 into my orignial equation which i thought was "wrong" and i got 13! which the right answer but i swear when i tried 3 times beofre i got the wring answer! sorry guys
17. i do appreciate your help anyway
18. no probz.....its good to see some easier questions lol....since I tend to be panicking over my own
19. (Original post by CKsuper1)
no probz.....its good to see some easier questions lol....since I tend to be panicking over my own
why? which module you doing at the moment?
20. (Original post by CKsuper1)
no probz.....its good to see some easier questions lol....since I tend to be panicking over my own
Have you done Analysis yet? Q 3,5 and most of 1 down!!! For some reason last night at about 4am everything clicked after staring at it for hours LOL

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Updated: November 9, 2008
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