Answer
$a.\quad x=-1,\ x=-0.25$ and $x=0.25$
$b.\quad x\in[-1,-0.25]\cup[0.25,\infty)$
Work Step by Step
$a.$
Graph $f(x)=16x^{3}+16x^{2}$ (red on the image)
and $g(x)=x+1$ (blue).
The solution (if it exists) is the x-coordinate of the intersection.
Solution: $x=-1,\ x=-0.25$ and $x=0.25$
$b.$
Using the graphs of part (a), we see that
the red graph is above or intersecting the blue graph on intervals
$[-1,-0.25]\cup[0.25,\infty)$
