Let $[x]$ represents the greatest integer not more than $x$. The discontinuous points of the function…

Let $[x]$ represents the greatest integer not more than $x$. The discontinuous points of the function $f(x)=\frac{5+[x]}{\sqrt{11+[x]-6 \sqrt{2+[x]}}}$ lies in the interval
  1. $[0, \infty)$
  2. $[5,8]$
  3. $[7,8)$
  4. $[7,10)$

Solution

Given the function, $f(x)=\frac{5+[x]}{\sqrt{11+[x]-6 \sqrt{2+[x]}}}$ for discontinuous points, if $x>0$ $\begin{aligned} & 11+[x]-6 \sqrt{2+[x]}=0 \Rightarrow(11+[x])^2=36(2+[x]) \\ & \Rightarrow[x]^2-14[x]+49=0 \Rightarrow([x]-7)^2=0 \\ & \Rightarrow[x]=7 \Rightarrow x \in[7,8) \end{aligned}$

Asked in: AP EAMCET 2023 (15 May Shift 2)

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