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# Differentiation problem.... y=xz watch

1. How would you differentiate this with respect to x??

(I think it would be dy/dx = z + x. dz/dx , but I'm not really sure why...) It came up on my FP2 and I can't really get my head around the method )

Any help would be brilliiant thanks!!
2. It's called the product rule.

When there is a product of variables it is necessary to calculate as follows:

y = uv

dy/dx = u.dv/dx + v.du/dx

Therefore your assumption would be correct. Sorry if my explanation is unclear. Hope this helps.
3. (Original post by TomSouthwell)
How would you differentiate this with respect to x??

(I think it would be dy/dx = z + x. dz/dx , but I'm not really sure why...) It came up on my FP2 and I can't really get my head around the method )

Any help would be brilliiant thanks!!
What you think it is is correct, assuming z is a function of x. You've basically used the product rule.

To do this we differentiate wrt x, using the product rule, "differentiate the first, leave the second, plus, leave the first differentiate the second."

So dy/dx = [1(z)]+[x. dz/dx]

Then simplifying things you get dy/dx
4. (Original post by Mr Blobby)
It's called the product rule.

When there is a product of variables it is necessary to calculate as follows:

y = uv

dy/dx = u.dv/dx + v.du/dx

Therefore your assumption would be correct. Sorry if my explanation is unclear. Hope this helps.
(Original post by dknt)
What you think it is is correct, assuming z is a function of x. You've basically used the product rule.

To do this we differentiate wrt x, using the product rule, "differentiate the first, leave the second, plus, leave the first differentiate the second."

So dy/dx = [1(z)]+[x. dz/dx]

Then simplifying things you get dy/dx
Ahh thanks guys, I didn't realise it was a form of the product rule! Thanks for clearing this us, rep for both of you
5. (Original post by dknt)
What you think it is is correct, assuming z is a function of x. You've basically used the product rule.

To do this we differentiate wrt x, using the product rule, "differentiate the first, leave the second, plus, leave the first differentiate the second."

So dy/dx = [1(z)]+[x. dz/dx]

Then simplifying things you get dy/dx
Oh, looking at your Sig. you might get Prof. Brian Cox as one of your lectures :P I have a friend in the year above at Manchester doing Physics who has him!
6. (Original post by TomSouthwell)
Oh, looking at your Sig. you might get Prof. Brian Cox as one of your lectures :P I have a friend in the year above at Manchester doing Physics who has him!
Awesome

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