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# C1 differentiation HELP!! watch

Find the gradient at the point x=-1 on the curve: y= x^2(2x^11+6x^4)

2. I have done this so far not sure it is it right
3. Times out the bracket then differentiate.

Then sub In x=-1
4. (Original post by avalerion)
Times out the bracket then differentiate.

Then sub In x=-1
Thank you I got 4 as the answer
5. I think you need to differentiate
6. (Original post by laila_a1)

I have done this so far not sure it is it right
You are right until you made dy/dx = -1
You need to sub in -1
7. (Original post by laila_a1)
Thank you I got 4 as the answer
Great! I like a nice whole number
8. (Original post by avalerion)
You are right until you made dy/dx = -1
No they aren't.

(Original post by laila_a1)
Thank you I got 4 as the answer
That's wrong.
9. (Original post by alow)
No they aren't.

That's wrong.
How?
10. (Original post by laila_a1)
How?
You expanded the bracket wrong. Look at my first post.
11. Check your powers when you expanded out the bracket.
12. (Original post by laila_a1)
How?
Alow has pointed out a very simple mistake you've made: that multiplying x^2 and x^11 does not give x^22. Instead the indices add.

13. (Original post by benjaminfinch)
Alow has pointed out a very simple mistake you've made: that multiplying x^2 and x^11 does not give x^22. Instead the indices add.

So would this be right
14. (Original post by laila_a1)
So would this be right
Yes. Well done.
15. (Original post by alow)
Yes. Well done.
Thank you, sorry I didn't understand you before
16. yeah, that's perfect well done

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