Question

решите пожалуйста, срочно надо​

Answer 1

$f(x)=\frac{x-2}{x^{2}+x-20 }\\\\x^{2}+x-20\neq0\\\\x_{1}\neq-5\\\\x_{2}\neq 4\\\\Otvet:\boxed{x\in(-\infty;-5)\cup(-5;4)\cup(4;+\infty)}\\\\\\2)f(x)=\sqrt{x+9}-\sqrt{4-x}\\\\\left \{ {{x+9\geq 0} \atop {4-x\geq0 }} \right.\\\\\left \{ {{x\geq-9 } \atop {x\leq4 }} \right. \\\\Otvet:\boxed{x\in[-9;4]}$

$3)f(x)=\frac{\sqrt{x+1} }{\sqrt{x-2}}-\frac{5x+2}{x^{2}-7x+12}\\\\\left \{ {{x+1\geq0;x-2>0 } \atop {x^{2}-7x+12\neq0}} \right.\\\\1)x+1\geq0\Rightarrow x\geq-1\\\\2)x-2>0\Rightarrow x>2\\\\3)x^{2}-7x+12\neq0\Rightarrow x_{1}\neq3;x_{2}\neq 4\\\\Otvet:\boxed{x\in(2;3)\cup(3;4)\cup(4;+\infty)}$