Find the cube of:

2a - 1

(2a - 1)³

Using the formula,

(x - y)³ = x³ - y³ - 3x²y + 3xy²

= (2a)³ - (1)³ - 3 $\times$ (2a)² $\times$ (1) + 3 $\times$ (2a) $\times$ (1)²

= 8a³ - 1 - 12a² + 6a

Hence, (2a - 1)³ = 8a³ - 1 - 12a² + 6a