(i) We know that,

(a + b)³ = a³ + b³ + 3ab (a + b)

Using this formula, we get

= (3x)³ + (2)³ + 3 × 3x × 2 (3x + 2)

= 27x³ + 8 + 18x (3x + 2)

= 27x³ + 8 + 54x² + 36x

(ii) We know that,

(a + b)³ = a³ + b³ + 3ab (a + b)

Using this formula, we get

= (3a)³ - (2b)³ - 3 × 3a × 2b (3a - 2)

= 27a³ – 8b³ – 18ab (3a – 2b)

= 27a³ – 8b³ – 54a²b + 36ab²

(iii) We know that,

(a + b)³ = a³ + b³ + 3ab (a + b)

Using this formula, we get

= (2/3x)³ + (1)³ + 3 × 2/3x × 1 (2/3x + 1)

= 8/27x³ + 1 + 2x (2/3x + 1)

=