答案 f'(x)=(sin mx)*2=1\2 (1-cos 2mx)
f(x)=1/2{ x-(sin 2mx)/2m}
是否对?
f'(x)=sin²(mx)=½[1-cos(2mx)]
f(x)=∫f'(x)dx=½∫[1-cos(2mx)]dx
=½[x-sin(2mx)/(2m)]+C