Carry out each specified substitution

Find (a) $\int x(2-3x)^{11}\,dx$, using $u=2-3x$; (b) $\int\frac{x+1}{x\sqrt{x-2}}\,dx$, using $u=\sqrt{x-2}$; (c) $\int\frac1{(x^2+4)^{3/2}}\,dx$, using $x=2\tan\theta$, $-\pi/2<\theta<\pi/2$; (d) $\int\frac{\sqrt{9-x^2}}{x^2}\,dx$, using $x=3\sin\theta$, $-\pi/2\le\theta\le\pi/2$.