Question

If $0<x^2\le 7$ then $x\in$

• A. $\left[-\sqrt{7},\sqrt{7}\right]$
• B. $\left[-\sqrt{7},\infty \right]$
• C. $\left[-\sqrt{7},\sqrt{7}\right]-\left(0\right)$
• D. None of these

Answer 1

Answer: (C)

$\left[-\sqrt{7},\sqrt{7}\right]-\left(0\right)$

$0<x^2\le 7$

then

$x\in [-\sqrt{7},\sqrt{7}]$

but $x^2\ne 0$

so we have to exclude $0$

from solution set

$x\in [-\sqrt{7},\sqrt{7}]-\left(0\right)$

$C$ is correct.