Solve this

Question:

Let $[t]$ denote the greatest integer $\leq t$. Then the equation in $x,[x]^{2}+2[x+2]-7=0$ has :

  1.  no integral solution

     

  2.  exactly four integral solutions

     

  3.  exactly two solutions

     

  4.  infinitely many solutions


Correct Option: , 4

Solution:

$[x]^{2}+2[x+2]-7=0$

$\Rightarrow[x]^{2}+2[x]+4-7=0$

$\Rightarrow[x]=1,-3$

$\Rightarrow x \in[1,2) \cup[-3,-2)$

 

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