if you meant to simplify
[tex] \bf 4(v^3)^2\implies 4(v^{3\cdot 2})\implies 4(v^6)\implies 4v^6\\\\\\(a^2b)^3\implies (a^2b^1)^3\implies \stackrel{\textit{distributing the exponent}}{(a^{2\cdot 3}b^{1\cdot 3})}\implies a^6b^3 [/tex]