How can obtain an expression for the maximum work

Question

Assume a gas obeys the equation of state P +an³/V³ = nRT/V where a is a constant.

1. How can obtain an expression for the maximum work the gas can do in the expansion if n moles of the gas undergo is other male expansion at the temperature T from an initial volume V₁ to a final volume V₂.

2. Develop an expression for the internal pressure P_t of the gas.