If x-1/x=5, then the value of x²+1/x² will be

(a) 5
(b) 25
(c) 27
(d) 23

Anurag Mishra Professor Asked on 29th February 2016 in Maths.
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1 Answer(s)

Answer: (c) 27

Solution:-
X – 1/X = 5
Square on both side, 
( X- 1/X)^2 = X^2 + 1/X^2 – 2 x X x 1/X
 (5)^2 = X^2 + 1/X^2 – 2
X^2 + 1/X^2 = 25 + 2
X^2 + 1/X^2 = 27

Then, the value of X^2 + 1/X^2 is 27. 

Hence, the correct answer is option (c) 27. 

Anurag Mishra Professor Answered on 2nd March 2016.
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