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## #1 Re: Help Me ! » Finding the derivative » 2006-04-25 14:41:20

oh. ok.
so for cos^4(2x)
the derivative would be
[cos²(2x)²]'=[2cos²(2x)]*[2cos(2x)]*[-sin(2x)][2]
=-8cos³(2x)sin(2x)

and the whole equation would be,

2y (dy/dx) = 8sin³(2x)cos(2x) - 8cos³(2x)sin(2x)
dy/dx  = {8sin(2x)cos(2x)[sin²(2x)-cos²(2x)]} / 2y

... but how do i go further?
i am supposed to make the dy/dx = (-sin8x)/y

thanx a lot for the answer

## #2 Help Me ! » Finding the derivative » 2006-04-25 12:33:49

silvercity87
Replies: 3

How do I find the derivative of

y^2=sin^4(2x)+cos^4(2x) ?

I know that for y^2, i have to use implicit differentiation.

But for sin^4(2x), is it like saying (sin^2(2x))^2??

## #3 Re: Help Me ! » Permutation » 2006-01-28 16:33:02

So in a similar question that goes
"How many 7 digit even numbers less than 3 000 000 can be formed using all the digits 1,2,2,3,5,5,6?", the answer would be

3*5*4*3*2*1*2 divide by 2*2=180 right?

I'm confused
Thank you for the answers though!

## #4 Re: Help Me ! » Permutation » 2006-01-28 13:28:13

But the number has to be odd as well :\$

## #5 Help Me ! » Permutation » 2006-01-28 13:00:12

silvercity87
Replies: 6

The question goes:
How many 6-digit odd numbers less than 200 000 can be formed using the digits 1,1,2,2,3 and 5?
How do I solve this kind of question? can anybody help me please?!!!: