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# Differential calculus

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1. I'm stuck with a function of a function?

I think I use the chain rule dy/dx = dy/du X du/dx

But I don't know what to do. Could someone explain it to me really simply please?
2. Say you have y = sin(4x).

A variation of the chain rule is to let u = 4x, v = sin(u).

Does that make sense?
3. (Original post by jami74)
I'm stuck with a function of a function?

I think I use the chain rule dy/dx = dy/du X du/dx

But I don't know what to do. Could someone explain it to me really simply please?
Its better that you give the question you are stuck on.
4. (Original post by ViralRiver)
Say you have y = sin(4x).

A variation of the chain rule is to let u = 4x, v = sin(u).

Does that make sense?
I'm looking at it very hard. If I keep looking it might make sense and then I can apply it to my question.

(Original post by raheem94)
Its better that you give the question you are stuck on.
Thank-you. It is y=cos^2x

So is u = cos^2?
5. (Original post by jami74)
I'm looking at it very hard. If I keep looking it might make sense and then I can apply it to my question.

Thank-you. It is y=cos^2x

So is u = cos^2?

Now find .

At the end, use the chain rule,
6. (Original post by raheem94)

Now find .

At the end, use the chain rule,
Thank-you.

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