1.y' = 2 sin (3x+π/6) + 6x cos (3x+π/6)
2.y' = sin2x + 2x cos 2x - 3 sinx
3.y' = 1/2 * 根号( (1-x)/x ) / (1-x) = 1/2 * (x*(1-x))^(1/2)
4.y = ln sin2x - ln x;
y' = csc2x * cos2x * 2 - 1/x