23x + 13=23x3 + 13 + 323x21 + 323x12=827x3 + 1 + 43x2 + 2xusing identity,a + b3 = a3 + b3 + 3a2b + 3ab2

expand ( 2/3x + 1)³

{(\frac{2}{3 x} + 1)}^{3} = {(\frac{2}{3 x})}^{3} + {(1)}^{3} + 3 {(\frac{2}{3 x})}^{2} (1) + 3 (\frac{2}{3 x}) {(1)}^{2} = \frac{8}{27 x^{3}} + 1 + \frac{4}{3 x^{2}} + \frac{2}{x} using identity, {(a + b)}^{3} = a^{3} + b^{3} + 3 a^{2} b + 3 {ab}^{2}

expand ( 2/3x + 1) 3