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# C4 further differentiation help watch

1. how do i find dy/dx of:

(1)
k) xcosy
l) x^2 e^2y
m) e^x y^2
n) 1/y
o) x/y^3

(2)
f) 2x^2 y and 5xy^2

2. What do you think the answers are? Remember that dy/dx is taking the derivative with respect to x.
3. (Original post by m:)ckel)
What do you think the answers are? Remember that dy/dx is taking the derivative with respect to x.
yeah i understand that
like for example k is cosy - xsiny dy/dx
but how/what method was used
4. (Original post by SeekerOfKnowledge)
yeah i understand that
like for example k is cosy - xsiny dy/dx
but how/what method was used
For things like that, you have to use implicit differentiation.

For example, for x*cos(y), you have to use the product rule on it where the first function is x and the second is cos(y).

From there, you get cos(y) + x * d/dx [cos(y)].

For the part that is d/dx [cos(y)], you simply use the chain rule.

-sin(y)*dy/dx - since dy/dx is the derivative of y.

For the other questions, just follow the normal differentiation rules (especially the chain rule) and treat 'y' as a function of y whose derivative is dy/dx.

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