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Answer:
a + (1 / a) = 5
a ^ 2 + (1 / a ^ 2) = 23
Step-by-step explanation:
Solution,
We have,
a^2 - 5a +1 = 0
a^2 + 1 = 5a
(a^2 + 1) / a = 5
(a^2 / a) + (1 / a) = 5
a + (1 / a) = 5
Hence, a + (1 / a) = 5
Now,
Again,
a + (1 / a) = 5
Squaring the both sides,
{ a + (1 / a) } ^ 2 = (5) ^ 2
a ^ 2 + 2 . a . (1 / a) + (1 / a) ^ 2 = 25
a ^ 2 + 2 + (1 / a ^ 2) = 25
a ^ 2 + (1 / a ^ 2) = 25 - 2
a ^ 2 + (1 / a ^ 2) = 23
Hence, a ^ 2 + (1 / a ^ 2) = 23
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