# derivative

• Apr 15th 2007, 08:22 AM
crazyhanna
derivative
can anyone plz help me find the derivtives to these equations??
cos3x/(2+sinx)

lnx/(x((lnx)^4)-1) x>0

dx/(2+sinx+2cosx)

sqr((x-3)/(x+3)
• Apr 15th 2007, 08:38 AM
qbkr21
Re:
Quote:

Originally Posted by crazyhanna
can anyone plz help me find the derivtives to these equations??
cos3x/(2+sinx)

lnx/(x((lnx)^4)-1) x>0

dx/(2+sinx+2cosx)

sqr((x-3)/(x+3)

Hold on and I will post the solutions; can you try to make #2 a bit neater. Is the x*ln(x)^4-1?
• Apr 15th 2007, 08:40 AM
topsquark
Quote:

Originally Posted by crazyhanna
can anyone plz help me find the derivtives to these equations??
cos3x/(2+sinx)

Use the quotient and chain rules together:
y = cos(3x)/(2+sin(x))

y' = [-sin(3x)*3 * (2 + sin(x)) - cos(3x) * (cos(x))]/[2 + sin(x)]^2

y' = -[3sin(3x)*(2 + sin(x)) + cos(x)*cos(3x)]/[2 + sin(x)]^2

-Dan
• Apr 15th 2007, 08:50 AM
Krizalid
Quote:

Originally Posted by crazyhanna
sqr((x-3)/(x+3)

Here it is...
• Apr 15th 2007, 08:58 AM
Krizalid
It shouldn't be dy/dx ?

Regards.
• Apr 15th 2007, 09:18 AM
qbkr21
Re:
RE: Good Point!!
• Apr 15th 2007, 09:23 AM
qbkr21
Re:
Quote:

Originally Posted by crazyhanna
can anyone plz help me find the derivtives to these equations??
cos3x/(2+sinx)

lnx/(x((lnx)^4)-1) x>0

dx/(2+sinx+2cosx)

sqr((x-3)/(x+3)

RE: