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Mathematics
Let A= x: x ∈ R ; x is not a positive integer Define f: A arrow R as f(x)=(2 x/x-1), then f is
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Q. Let $A=\{x: x \in R ; x$ is not a positive integer $\}$ Define $f: A \rightarrow R$ as $f(x)=\frac{2 x}{x-1}$, then $f$ is
KCET
KCET 2021
Relations and Functions - Part 2
A
injective but not surjective
30%
B
surjective but not injective
20%
C
bijective
31%
D
neither injective nor suriective
18%
Solution:
$f'(x)=\frac{-2}{(x-1)^{2}}<0$
$f$ is s.d. $f$ is one-one
$\frac{2 x}{x-1}=y$
$\Rightarrow x=\frac{y}{y-2} \notin \pi$
for $y=2f$ is not out