How to Solve Integrals with Substitution Techniques?

[femmed0ll]

41) ∫ (xdx) / (7x^2 + 3)^5

42) ∫ (sint) / (3 + cos t)^3 dthow do i solve this? i have no idea where to start...can you have a step by step process/analysis on how to figure out the answer? thanks!

 

[mathman]

Substitution:
41) u=x²
42) u=cos t