NOTE: I use ( as the beggining intergral sign... so ( x^2 dx is the integral of x^2.

1.I have two integrals. (tan x sec^2 x dx and (sin x / cos^3 x dx

-after looking at them I realize they are the same thing...

-then why do i get different answers?

1) u =tan x du=sec^2 x dx ((u)du = u^2 /2. Answer is

**(tan^2 x/2) + C**
2) u =cosx du=-sinx dx -du=sinx dx (-du/(u)^3= (u)^-2/2. Answer is

**(sec^2 x)/2 + C**
What am I doing wrong?

2. (tan(3x) dx

- I got the answer -1/3 ln cos(3x) +C. I was wondering if I should an absolute value around COS 3x or not. Should I?

3.( x(2+x)^.5 dx

-how do i do this one?

- this is how far i got. u= 2+x du=1 ( du(x) (u)^.5 I am lost now.

-Thanks for the help in advance