Question

Expand each of the following using suitable identities (x-2/3y)³

Answer 1

${(a - b)}^{3} = {a}^{3} - {b}^{3} - 3 {a}^{2} b + 3a {b}^{2} \\ {(x - \frac{2}{3}y) }^{3} = {x}^{3} - \frac{8}{27} {y}^{3} - 2 {x}^{2} y + \frac{3}{4} x {y}^{2}$