Posted by **sh** on Sunday, March 21, 2010 at 11:02pm.

Find the derivative of y with respect to x:

y=(1+cos²x)^6

y'=6(1+cos²x)^5

How do you derive inside the brackets? The answer says -sin2x, but wouldn't it be -2sinx, using the chain rule.

- Calculus -
**Reiny**, Sunday, March 21, 2010 at 11:06pm
You still have to differentiate the "inside"

d(1+cos^2x) = 2cosx(-sinx)

= -2sinxcox

= -sin 2x, one of the identities

so

y'=6(1+cos²x)^5(-sin2x)

= y'= -6(1+cos²x)^5(sin2x)

- Calculus -
**sh**, Sunday, March 21, 2010 at 11:30pm
Oh, I see it now, thanks!

## Answer this Question

## Related Questions

- Calculus 12th grade (double check my work please) - 1.)Find dy/dx when y= Ln (...
- Math, derivatives - Let g(x) = sin (cos x^3) Find g ' (x): The choices are a) -...
- Calculus - Find the derivative of f(x) =cos^-1(x^2) Ok so I'm having a little ...
- Calculus - Find f'(x) if f(x)=sin^3(4x) A. 4cos^3(4x) B. 3sin^2(4x)cos(4x) C. ...
- calculus - Could someone check my reasoning? thanx Find the derivative of the ...
- calculus-derivatives - y=cos^3(12theta) find derivative using chain rule
- Calculus - Find the outside and inside functions of the following to find their ...
- math - Find the exact value of cos 300 degrees. thanks guys cos 300 = 1/2 = 0....
- Cos-Derivative - y= (cos^3 x) (cos 3x) I got -3 sin(3x) cos^3x - 3 sin(x) cos (...
- Calculus - Use implicit differentiation to find dy/dx. e^4x = sin(x+2y). This is...