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1.Relation and Function
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The mid-point of the domain of the function $f(x)=\sqrt{4-\sqrt{2 x+5}}$ real $x$ is
A
$\frac{1}{4}$
B
$\frac{3}{2}$
C
$\frac{2}{3}$
D
$-\frac{2}{5}$
(KVPY-2012)
Solution
(b)
We have, $f(x)=\sqrt{4-\sqrt{2 x+5}}$
$f(x)$ is defined if
$4-\sqrt{2 x+5} \geq 0$ and $2 x+5 \geq 0$
$\Rightarrow 4 \geq \sqrt{2 x+5}$ and $x \geq-5 / 2$
$\Rightarrow 16 \geq 2 x+5$ and $x \geq-5 / 2$
$\Rightarrow x \leq \frac{11}{2}$ and $x \geq-5 / 2$
$\therefore$ Domain of $f(x) x \in\left[\frac{-5}{2}, \frac{11}{2}\right]$
Mid-point of domain $\frac{\frac{-5}{2}+\frac{11}{2}}{2}=\frac{3}{2}$
Standard 12
Mathematics