The domain of the real valued function $f(x)=\frac{\log _2(x+3)}{\sqrt{x^2+3 x+2}}$ is

The domain of the real valued function $f(x)=\frac{\log _2(x+3)}{\sqrt{x^2+3 x+2}}$ is
  1. $(-3, \infty)$
  2. $(-3,-1) \cup(-1, \infty)$
  3. $(-3,-2) \cup(-2,-1) \cup(-1, \infty)$
  4. $(-3,-2) \cup(-1, \infty)$

Solution

$ \begin{aligned} & \text { Given, } f(x)=\frac{\log _2(x+3)}{\sqrt{x^2+3 x+2}} \\ & \\ & \quad x^2+3 x+2>0 \\ & \Rightarrow \quad x^2+2 x+x+2>0 \\ & \Rightarrow \quad x(x+2)+1(x+2)>0 \\ & \Rightarrow \quad(x+2)(x+1)>0 \\ & \Rightarrow \quad x \in(-\infty,-2) \cup(-1, \infty) \\ & \text { But } x+3>0 \\ & \quad x>-3 \end{aligned} $ Hence, $x \in(-3,-2) \cup(-1, \infty)$

Asked in: AP EAMCET 2022 (06 Jul Shift 2)

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