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Question
If a ≠ 0 and `a - 1/a` = 4; find: `(a^2 + 1/a^2)`
Sum
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Solution
`( a - 1/a )^2 = a^2 + 1/a^2 - 2`
⇒ `a^2 + 1/a^2 = ( a - 1/a )^2 + 2`
⇒ `a^2 + 1/a^2 = (4)^2 + 2 [ ∵ a - 1/a = 4]`
⇒ `a^2 + 1/a^2` = 18
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