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# Chain Rule-Differentation watch

1. Could anyone help me in this question can't seem to work it out.

Here is the mark scheme:

I don't seem to get how they got rid of the 1 in tan4x, I always thought when you use the chain rule and have a power on the top, you multiply down by that power, and rewrite the inside function and then multiply by the derivative of the inside function??

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2. Anyone?

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3. (Original post by Jimmy20002012)
...
I assume you are trying to differentiate the expression in first line.
In which case, your second line of working does not follow from the first.
Try expanding out the brackets before differentiating.
4. (Original post by Jimmy20002012)
Could anyone help me in this question can't seem to work it out.

Here is the mark scheme:

I don't seem to get how they got rid of the 1 in tan4x, I always thought when you use the chain rule and have a power on the top, you multiply down by that power, and rewrite the inside function and then multiply by the derivative of the inside function??

Posted from TSR Mobile
What function are you trying to differentiate?

On the first line you have

but on the second line you have

and these are two completely different functions!

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Updated: December 24, 2014
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