If f(x)=x−[x],x(≠0)∈R , where [x] is the greatest integer less than or equal to x , then the number of solutions of f(x)+f(1x)=1 is
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a
0
b
1
c
Infinite
d
2
answer is C.
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Detailed Solution
Given that f(x)=x−[x], ⇒f(1x)=1x−[1x] We have: f(x)+f(1x)=1 ⇒x−[x]+1x−[1x]=1 ⇒x+1x−1=[x]+[1x] ⇒x2+1−xx= Integer k (say)⇒x2−(k+1)x+1=0 Since x is real,∴ (k+1)2−4≥0 (∵ b2−4ac≥0) ⇒k2+2k−3≥0 ⇒(k+3)(k−1)≥0 ⇒k≤−3 or k≥1 .Hence the number of solutions is infinite.