1. The problem statement, all variables and given/known data 1.∫sec^2 (4x+1)dx 2.∫ root(sin pi theta) cos(pi theta) d(theta) 3.∫ e^x dx /(1+e^x) 2. Relevant equations 1.u=4x+1 2. u= sin(pi theta) 3. u= 1+e^x antiderivatives to find the answers.. 3. The attempt at a solution For #1, tan^4(4x+1)/4 +c..is the answer..but I don't get why tan should be ^4?? I took the deriv. of the u and replace dx with the stuff that only contains du..not dx... And then,,I sometimes have problems solving some questions.. Please help!