Question

Даю 25 баллов! Писать нужно азвёрнуто, т.е не только ответ!

Answer 1

$\displaystyle\bf\\2)\\\\\frac{x^{2} -16}{x+4} =0\\\\\\\frac{(x+4)(x-4)}{x+4} =0\\\\\\\left \{ {{(x+4)(x-4)=0} \atop {x+4\neq 0}} \right. \\\\\\\left \{ {{x-4=0} \atop {x\neq -4}} \right. \\\\\\Otvet:x=4\\\\\\2)\\\\\frac{x+2}{x^{2} -4} =0\\\\\\\frac{x+2}{(x+2)(x-2)} =0\\\\\\\left \{ {{x+2=0} \atop {(x+2)\neq 0 \ , \ x-2)\neq 0}} \right. \\\\\\Otvet:x\in\oslash$

$\displaystyle\bf\\3)\\\\\frac{5}{x+7} -\frac{3}{x-7} =0\\\\\\\frac{5\cdot(x-7)-3\cdot(x+7)}{(x+7)(x-7)} =0\\\\\\\frac{5x-35-3x-21}{(x+7)(x-7)} =0\\\\\\\frac{2x-56}{(x+7)(x-7)}=0\\\\\\\left\{\begin{array}{ccc}2x-56=0\\x+7\neq 0\\x-7\neq 0\end{array}\right\\\\\\\left\{\begin{array}{ccc}x=28\\x\neq -7\\x\neq 7\end{array}\right\\\\\\Otvet:28$