# Chain Rule

• Nov 19th 2007, 08:52 PM
Truthbetold
Chain Rule
Find dy/dx.

$\displaystyle y= sin^5 x - cos^3 x$
The exponent 5 is negative. I don't know the LaTex.

I understand the chain rule. I do not understand how to do this.
Which function is outer f(x) and which is inner g(x)?

Thanks!
• Nov 19th 2007, 08:56 PM
Jhevon
Quote:

Originally Posted by Truthbetold
Find dy/dx.

$\displaystyle y= sin^5 x - cos^3 x$
The exponent 5 is negative. I don't know the LaTex.

I understand the chain rule. I do not understand how to do this.
Which function is outer f(x) and which is inner g(x)?

Thanks!

$\displaystyle \sin^{-5} x - \cos^3 x = ( \sin^{-1} x)^5 + (\cos x )^3$

do you see the inner and outer functions now?
• Nov 19th 2007, 09:06 PM
Truthbetold
Won't the derivative of -5 equal 0?
Constant rule.

That doesn't make much sense, though. Something's wrong.

What do you do for this?

Thanks!
• Nov 19th 2007, 09:11 PM
Jhevon
Quote:

Originally Posted by Truthbetold
Won't the derivative of -5 equal 0?
Constant rule.

That doesn't make much sense, though. Something's wrong.

What do you do for this?

Thanks!

the derivative of a constant is zero. where do you see a constant here? 5 is a power, for all intents and purposes, it is a part of the sine function we are dealing with. if it was just a 5 by itself, then yes, it goes to zero, that is not the case here. use the chain rule (with the power rule)