+2 +1 +2 +2x2+1-1 解 x2+1 +1 ∫(x2+1)k-「 x'+x-arctanx+C () cos dx 解∫∞32=+xk=1(+im+C5 4 2 2 2 (2) 1 x x dx x 4 2 4 2 2 2 2 2 1 1 1 1 x x x x dx dx x x 解 2 2 2 ( 1) 1 1 x dx x 2 2 1 ( 1) 1 x dx dx x 1 3 arctan 3 x x x C 2 (3) cos 2 xdx 2 1 cos cos 2 2 x x dx dx 解 1 ( sin ) 2 x x C