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Question
Write the following cube in expanded form:
`[x-2/3y]^3`
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Solution
(x - y)3 = x3 - y3 - 3xy(x - y)
Using Identity
`[x - 2/3y]^3 = x^3 - (2/3y)^3 - 3(x)(2/3y)(x - 2/3y)`
= `x^3 - 8/27y^3 - 2xy(x - 2/3y)`
= `x^3 - 8/27y^3 - 2x^2y + 4/3xy^2`
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