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# C3 Differentiation URGENT HELP! watch

1. c3 book Exercise 8B question D. I cant get the final answer even though i think my working is correct. Can someone explain the steps clearly please.
2. (Original post by JSM1)
c3 book Exercise 8B question D. I cant get the final answer even though i think my working is correct. Can someone explain the steps clearly please.
What board? OCR Mei ?
3. (Original post by Rachmaninov)
What board? OCR Mei ?
edexcel
4. This is the question
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5. (Original post by JSM1)
This is the question

You can use the quotient rule from here
6. I dont get the right final answer
7. this is my working out
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8. help
9. (Original post by JSM1)
help
Second to last step is wrong
10. Mate, use the quotient rule, so much easier

3x^2
———
(5x-1)

=

U

V
11. what do i do in that step?
12. How do i go from that step to the last?
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13. dy/dx

=

vu’ - uv’
————
v^2

Where u’ is u differentiated (and v’ is v differentiated)
14. Its not the quotient rule. Its the product rule and i have the correct working out but i don't understand how to go from the penultimate step to the final answer.
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15. Turn the step third from last into fractions. Should make it easier.

Basically from the third-from-last step to the second-from-last step, you have screwed up the powers
16. (Original post by JSM1)
Its not the quotient rule. Its the product rule and i have the correct working out but i don't understand how to go from the penultimate step to the final answer.
Arghhh yes, you can use the product rule, but you may notice that raising something to a negative power effectively turns it into a fraction. Honestly, it is easier if you use the quotient rule... unless it explicitly says to use the product rule (in which case sort out those aforementioned steps)
17. I still cant see where ive gone wrong or what to change. My working out is almost identical to that working out from the mark scheme. The powers seem fine as well.
18. (Original post by JSM1)
I still cant see where ive gone wrong or what to change. My working out is almost identical to that working out from the mark scheme. The powers seem fine as well.
... check the powers again mate. Failing that, express it as a fraction, and you may see where it’s all gone wrong
19. don't worry. I worked it out
20. I had to expand, simplify and factorise. the rest was correct

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