antidifferentiation of

(x^3)/squareroot((3x^4)+5) dx

i know the formula 1/square root(1 - x^2) but that doesnt help me.

can some one please check this one for me

antidifferentiation

sin^2xcos^2x dx

i got 1/3sinx^3 - 1/2sinx^4 + 1/5sin^5 + C

not very confident with this answer

also could some one check the antidifferentiation of

sin3xcos4x dx

i got 1/4sinx - 1/14sinx + C

thanks in advance