Answer:
[tex]10 v^{3}-18 v^{2}+12 v[/tex]
Step-by-step explanation:
[tex]\begin{array}{l}\left(5 v^{3}-9 v^{2}+6 v\right)-\left(-5 v^{3}+9 v^{2}-6 v\right) \\\\=5 v^{3}-9 v^{2}+6 v+5 v^{3}-9 v^{2}+6 v \\\\=\left(5 v^{3}+5 v^{3}\right)-\left(9 v^{2}+9 v^{2}\right)+(6 v+6 v) \\\\=10 v^{3}-18 v^{2}+12 v\end{array}[/tex]
