.. In each part, find the critical points, and decide whether the function has an absolute maximum and absolute minimum on the given interval; if so, please give the x-coordinates

of the absolute extrema.Be flexible; you don't need to use the same strategy for each part! \text { (a) } f(x)=x^{3}-6 x^{2}+9 x+7 \text { on }[-2,6] \text { (b) } g(x)=3 x^{2 / 3}-x \text { on the interval }[-1,1] \text { (c) } f(t)=\frac{1}{t}-\frac{2}{t^{2}} \text { on }[1, \infty) \text { (d) } f(x)=|\ln (x+3)| \text { on the interval }[-2.5, \infty) \text { . }