What is the dimensional formula of a b^ -1 in the equation (P+ a...

\because[\mathrm{V}]=[\mathrm{b}] \therefore$Dimension of$b=\left[\mathrm{L}^3\right] $$\begin{aligned} & &[\mathrm{P}]=\left[\frac{\mathrm{a}}{\mathrm{V}^2}\right] \\ & {[\mathrm{a}]=\left[\mathrm{PV}^2\right]=\left[\mathrm{ML}^{-1} \mathrm{~T}^{-2}\right]\left[\mathrm{L}^6\right]} \end{aligned}$$$Dimension of$\mathrm{a}=\left[\mathrm{ML}^5 \mathrm{~T}^{-2}\right] \therefore \mathrm{ab}^{-1}=\frac{\left[\mathrm{ML}^5 \mathrm{~T}^{-2}\right]}{\left[\mathrm{L}^3\right]}=\left[\mathrm{ML}^2 \mathrm{~T}^{-2}\right]