Here, we will use below formulas:
`(x+y)^3 =x^3+y^3+3xy(x+y)`
`(x-y)^3 =x^3-y^3-3xy(x-y)`
(i) `(2x+1)^3 = (2x)^3 +(1)^3 + 3*2x*1(2x+1)`
`= 8x^3+1+12x^2+6x = 8x^3+12x^2+6x+1`
(ii)`(2a-3b)^2 = (2a)^3 -(3b)^3 -3*2a*3b(2a-3b)`
`=8a^3-27b^3-36a^2b+54ab^2`
(iii)`(3/2x+1)^3 = (3/2x)^3+1^3+3*3/2x*1(3/2x+1)`
`=27/8x^3+27/4x^2+9/2x+1`
(iv)`(x-2/3y)^3 = x^3-(2/3y)^3-3*x*(2/3y)(x-2/3y)`
`x^3-8/27y^3-2x^2y+4/3xy^2`
