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Question
Expand.
`(x/3 - 3/x)^3`
Sum
Solution
`(x/3 - 3/x)^3`
(a − b)3 = a3 − 3a2b + 3ab2 − b3
= `(x/3)^3 - 3 xx (x/3)^2 xx (3/x) + 3 xx (x/3) xx (3/x)^2 - (3/x)^3`
= `(x^3)/27 - 3 xx (x^2)/9 xx 3/x + 3 xx x/3 xx 9/(x^2) - 27/(x^3)`
= `(x^3)/27 - (3x)/9 xx 3/1 + 3/3 xx 9/x - 27/(x^3)`
= `(x^3)/27 - (3x)/3 + 9/x - 27/(x^3)`
= `(x^3)/27 - x + 9/x - 27/(x^3)`
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