Question

Write the following cube in expanded form:- (2x + 1)³ 

Answer 1

It is known that,

(a + b)³ = a³ + b³ + 3ab(a + b)  and  (a - b)³ = a³ - b³ - 3ab(a - b)

(2x+1)³ = (2x)³+1³+(3×2x×1)(2x+1)

             = 8x³+1+6x(2x+1)

             = 8x³+12x³+6x+1