Answer
$ a.\quad\infty$.
$ b.\quad-\infty$.
$ c.\quad-\infty$.
$ d.\quad\infty$.
Work Step by Step
See screenshot below.
$ a.\quad$
Nearing $x=0$ from the left, the graph rises without bound. $\displaystyle \lim_{x\rightarrow 0^{-}}f(x)=\infty$.
$ b.\quad$
Nearing $x=0$ from the right, the graph falls without bound. $\displaystyle \lim_{x\rightarrow 0^{+}}f(x)=-\infty$.
$ c.\quad$
Nearing $x=1$ from the left, the graph falls without bound. $\displaystyle \lim_{x\rightarrow 1^{-}}f(x)=-\infty$.
$ d.\quad$
Nearing $x=1$ from the right, the graph rises without bound. $\displaystyle \lim_{x\rightarrow 1^{+}}f(x)=\infty$.
