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# URGENT is this correct? MATHS INTEGRATION watch

1. The gradient of the curve is given by dy/dx= (x^2+3)^2 divided by x^2, x is not 0
(A) Show that day/dx = x^2+6+9x^-2
The point. (3,20) lies on C
(B) find an equation for the curve C in the form y=f(x)
I have got:
X^2 divided by 2/3 +3/2(x^2)
Y=(x^2+6+9x^-2) +c
20= 3(x^2+6+9x^-2) +c
20= 3x^2 +18 +27x^-2 +c
3x^2+27x^-2-2+c
2. I got: Attachment 723630
(Ignore the other image that was before I saw you have a coordinate)
Attached Images

3. (Original post by RantingWhovian)
I got: Attachment 723630
The last term is incorrect. You need to divide the 9x^(-2) by the -2, not by -1.
4. (Original post by VannR)
The last term is incorrect. You need to divide the 9x^(-2) by the -2, not by -1.
I don’t use a method, I just do it in my head. Surely if you differentiate -9x^-1 you get 9x^-2, so that would work??
5. (Original post by RantingWhovian)
I don’t use a method, I just do it in my head. Surely if you differentiate -9x^-1 you get 9x^-2, so that would work??
Hahaha yeah, you're right, the method is that you divide by the exponent plus 1.....which is -1 in this case! Please forgive, I'm a second-year mathematics student who has not integrated a simple polynomial in months
6. (Original post by RantingWhovian)
I got: Attachment 723630
(Ignore the other image that was before I saw you have a coordinate)
+ c needed
7. (Original post by Muttley79)
+ c needed
I said ignore this one
8. (Original post by VannR)
Hahaha yeah, you're right, the method is that you divide by the exponent plus 1.....which is -1 in this case! Please forgive, I'm a second-year mathematics student who has not integrated a simple polynomial in months
I’ve never been taught it before 😄
9. (Original post by RantingWhovian)
I said ignore this one
So why did you leave it there? Just delete the post!
10. (Original post by Muttley79)
So why did you leave it there? Just delete the post!
I tried to! I’m not stupid. I had originally put it then saw the other part of OP’s post and changed my answer. I thought I’d deleted the other attachment but saw it and added the bracket. The app won’t let me delete the post

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Updated: February 8, 2018
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