MCQ
The equation $x^2-4 x+[x]+3=x[x]$, where $[x]$ denotes the greatest integer function, has:
  • A
    exactly two solutions in $(-\infty, \infty)$
  • B
    no solution
  • C
    a unique solution in $(-\infty, 1)$
  • a unique solution in $(-\infty, \infty)$

Answer

Correct option: D.
a unique solution in $(-\infty, \infty)$
d
$x^2-4 x+[x]+3=x[x]$

$\Rightarrow x^2-4 x+3=x[x]-[x]$

$\Rightarrow(x-1)(x-3)=[x] .(x-1)$

$\Rightarrow x=1 \text { or } x-3=[x]$

$\Rightarrow x-[x]=3$

$\Rightarrow\{x\}=3 \text { (Not Possible) }$

Only one solution $x=1$ in $(-\infty, \infty)$

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