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f(x + (1/x)) = x^2 + (1/x)^2
= x^2 + (1/x)^2 + 2*x*(1/x) - 2*x*(1/x)
= (x + (1/x))^2 - 2

Replace (x + (1/x)) by say 't', the equation becomes

f(t) = t^2 - 2
or f(x) = x^2 - 2

So answer is 'C'.

by pasami

Tue Aug 23, 2011 11:42 am
Forum: Data Sufficiency
Topic: function concept
Replies: 4
Views: 1317

function concept

If f(x+(1/x)) = x^2 + (1/x)^2
What is the value of f(x)?

A. x^2 + 1
B. x + (1/x)
C. x^2 - 2
D. x^2 + 2
E. x^2 + 2x

by pasami

Mon Aug 22, 2011 7:36 am
Forum: Data Sufficiency
Topic: function concept
Replies: 4
Views: 1317