Question

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

Answer 1

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