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Question
If `2"x"-1/(2"x")=4`, find: `8"x"^3-1/(8"x"^3)`
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Solution
`2"x"-1/"2x"=4`
`⇒(2"x"-1/"2x")^3=(4)^3`
`⇒(2"x")^3-(1/"2x")^3-3xx2"x"xx1/"2x"(2"x"-1/"2x")=64`
`⇒8"x"^3-1/"8x"^3-3(4)=64`
`⇒8"x"^3-1/"8x"^3-12=64`
`⇒8"x"^3-1/"8x"^3=64+12`
`⇒8"x"^3-1/"8x"^3=76`
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