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# fp2 help substiution in second order equations

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Why bother with a post grad? Are they even worth it? Have your say! 26-10-2016
1. can someone please help how do i get d2y/dx2 if ive got (cosx.dy/dx)=dy/dx
2. You will have to use implicit differentiation for questions like these. Not sure if what you got is right though? How did you do it?
3. (Original post by B_9710)
You will have to use implicit differentiation for questions like these. Not sure if what you got is right though? How did you do it?
Sorry i meant to say dy/dx=cosx.dy/dz how would i proceed to find d2y/dx2
4. Ok. That's looks right (I'm trusting you here ). So we need to differentiate both sides with respect to x. To differentiate the RHS we need to use the product rule.
So we have .
I assume your trouble is differentiating the second term.
.
From the substitution you have been given you should be able to find an expression for dz/dx.
Hope this helps.
5. (Original post by B_9710)
Ok. That's looks right (I'm trusting you here ). So we need to differentiate both sides with respect to x. To differentiate the RHS we need to use the product rule.
So we have .
I assume your trouble is differentiating the second term.
.
From the substitution you have been given you should be able to find an expression for dz/dx.
Hope this helps.
Thank you so much! Do you mind if over the next couple of days I send any more questions I get stuck on to you . Your explanation was very helpful
6. (Original post by Cookie2314)
Thank you so much! Do you mind if over the next couple of days I send any more questions I get stuck on to you . Your explanation was very helpful
That would be fine.
7. m1 im confused about part a-how is reaction force of the lift equal to the downward forces of albert and bella, surely you can only use the masses for the downwards force

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