If $l o g_{10} (x^{2} - 21) = 2$ , then find the value of $x$ .

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Solution

The correct option is C $\pm 11$
Given, $l o g_{10} (x^{2} - 21) = 2$
So,
$(x^{2} - 21) = 10^{2}$
$x^{2} - 21 = 100$
$x^{2} = 121$
Taking square root on both sides, we get
$x = \pm 11$

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