Question

найдите область определения функции: f(x) = ln(x^2-21)

Answer 1

$f(x)=ln(x^2-21)\\\\OOF:\; \; x^2-21>0\\\\(x-\sqrt{21})(x+\sqrt{21})>0\\\\+++(-\sqrt{21})---(\sqrt{21})+++\\\\x\in (-\infty ,-\sqrt{21})\cup (\sqrt{21},+\infty )$