Question

x - 1/3 y whole cube expand​

Answer 1

(x - y/3)³ = x³ - y³/27 - 3(x)(y/3)[x - y/3]

(x - y/3)³ = x³ - y³/27 - x²y + xy²/3

___(Ans.))

It is based on a formula of (a - b)³

Which equals ;

a³ - b³ -3ab(a - b)

Hope it helps.

^___°

Answer 2

= (x-1/3y)³

= x³ - 1/9 y³ - 3.x.1/3y(x-1/3y)

= x³ - 1/9 y³ - xy(x-1/3 y)

It is an algebraic identity in which we used a formula to solve this i.e.

(a-b)³ = a³ - b³ -3ab(a-b)

Some other identities :-

(a+b)³ = a³ + b³ + 3ab(a+b)

a³ + b³ = (a+b) (a² + b² - ab)

a³ - b³ = (a-b) (a² + b² + ab)