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# C4 help please watch

1. Q13

I found dy/dx= (-3y-2x) / (3x-2y)

I subbed in (1,1) and got dy/dx = -5 which is correct.

Now I need to find d2y/dx2, I got (22y-18x) / (3x-2y).

When I subbed in (1,1) I got 4, but the answer is 78

Dunno where I went wrong?
2. My working to get d^2y/dx^x.

I don't think that's clear enough.
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3. (Original post by Vorsah)
Q13
Would you mind posting the whole question as it appears in the textbook?

(Original post by Vorsah)
My working to get d^2y/dx^x.

I don't think that's clear enough.
It really isn't clear enough to make out most parts.
4. (Original post by Vorsah)
Q13

I found dy/dx= (-3y-2x) / (3x-2y)

I subbed in (1,1) and got dy/dx = -5 which is correct.

Now I need to find d2y/dx2, I got (22y-18x) / (3x-2y).

When I subbed in (1,1) I got 4, but the answer is 78

Dunno where I went wrong?
Rearrange to get then differentiate being very careful with the product rule and implicit differentiation and the answer comes out to 78 as required.
5. (Original post by brianeverit)
Rearrange to get then differentiate being very careful with the product rule and implicit differentiation and the answer comes out to 78 as required.
I got the correct answer, but I need help with this it looks simple but I'm sure which one is correct:

Ignore this it's the wrong one.
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6. (Original post by brianeverit)
Rearrange to get then differentiate being very careful with the product rule and implicit differentiation and the answer comes out to 78 as required.
Is it 1 or 2?
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7. (Original post by Vorsah)
Is it 1 or 2?
Neither is correct
Assuming I* have read waht you have written correctly

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