Answer
$\dfrac{5}{6}x^{4}-7x^{3}-19$
Work Step by Step
$\dfrac{2}{3}x^{4}+12x^{3}+\dfrac{1}{6}x^{4}-19x^{3}-19$
Simplify by combining like terms:
$\Big(\dfrac{2}{3}+\dfrac{1}{6}\Big)x^{4}+(12-19)x^{3}-19=...$
$...=\Big(\dfrac{12+3}{18}\Big)x^{4}-7x^{3}-19=\dfrac{15}{18}x^{4}-7x^{3}-19=...$
$...=\dfrac{5}{6}x^{4}-7x^{3}-19$
