Algebra problem

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yalanand: Senior | Next Rank: 100 Posts; Posts: 79; Joined: Wed Feb 06, 2008 7:52 am; Thanked: 2 times; GMAT Score:620

by yalanand » Sun Feb 01, 2009 12:17 am

If x - (1/x) = 1/2, then what is the value of x^2 + (1/x^2)?

(A) 1/4
(B) 3/4
(C) 5/4
(D) 7/4
(E) 9/4

Source: Beat The GMAT — Problem Solving | Sun Feb 01, 2009 12:17 am

piyush_nitt: Master | Next Rank: 500 Posts; Posts: 424; Joined: Sun Dec 07, 2008 5:15 pm; Location: Sydney; Thanked: 12 times

by piyush_nitt » Sun Feb 01, 2009 12:37 am

yalanand wrote:If x - (1/x) = 1/2, then what is the value of x^2 + (1/x^2)?

(A) 1/4
(B) 3/4
(C) 5/4
(D) 7/4
(E) 9/4

IMO E

x - (1/x) = 1/2

squaring both sides

x^2+ (1/x)^2 - 2 = 1/4

x^2+ (1/x)^2 = 1/4+2

= 9/4

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