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May 9th, 2017, 01:05 PM   #1
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so many errors...derivative

x/sin^2(x)

x does not go with the 2 up
like sin(x)

you have to use quotient rule

f'(x)g(x)-g'(x)f(x)/(g(x))^2

f'= is 1
but g'?
Little bit confused.
Isn't it chain rule?

Last edited by skipjack; May 10th, 2017 at 10:20 PM.
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May 9th, 2017, 01:14 PM   #2
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It's the power rule and the chain rule: $(\sin^2(x))'=2\cdot\sin(x)\cdot\cos(x)$.
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May 10th, 2017, 10:04 AM   #3
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Quote:
Originally Posted by Bobbyjoe View Post
x/sin^2(x)

x does not go with the 2 up
like sin(x)

you have to use quotient rule

f'(x)g(x)-g'(x)f(x)/(g(x))^2

f'= is 1
but g'?
Little bit confused.
Isn't it chain rule?
Yes, it is. Let u= sin(x) so that g(u)= u^2. Then dg/du = 2u and du/dx = cos(x). By the chain rule, dg(u)/dx = (dg/du)(du/dx) = (2u)(cos(x)) = 2 sin(x) cos(x).

Last edited by skipjack; May 10th, 2017 at 10:22 PM.
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