Answer
$13x^{3}$ + 1
Work Step by Step
(12$x^{3} - x^{2}- x + \frac{4}{3}$) + ($x^{3} + x^{2} + x - \frac{1}{3}$)
The like terms are 12$x^{3}$ and $x^{3} $(both containing $x^{3}$) , -$x^{2}$ and $x^{2}$ (both containing $x^{2}$) , -x and x (both containing r) , $\frac{4}{3}$ and -$\frac{1}{3}$ both are constants
We begin by grouping these pairs of like terms
= (12$x^{3}$ + $x^{3} $) + (-$x^{2}$ + $x^{2}$) + (-x + x)+ ($\frac{4}{3}$ - $\frac{1}{3}$)
=$13x^{3}$ + 1