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Question
Simplify:
`("a" + 1/"a")^3 - ("a" - 1/"a")^3`
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Solution
`("a" + 1/"a")^3 - ("a" - 1/"a")^3`
= `("a")3 + (1/"a")^3 + 3("a")(1/"a")("a" + 1/"a") - [("a")^3 - (1/"a")^3 = -3("a")(1/"a")("a" - 1/"a")]`
= `"a"^3 + (1)/"a"^3 + 3("a" + 1/"a") - ["a"^3 - 1/"a"^3 - 3("a" - 1/"a")]`
= `"a"^3 + (1)/"a"^3 + 3"a" + (3)/"a" - "a"^3 + (1)/"a"^3 + 3"a" - (3)/"a"`
= `(2)/"a"^3 + 6"a"`.
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