Question

x+3/x-7-6/x+7=140/x^2-49 срочно помогите

Answer 1

$\frac{x+3}{x-7}-\frac6{x+7}=\frac{140}{x^2-49}\\\\O.D.3.:\\\begin{cases}x-7\neq0\\x+7\neq0\\x^2-49\neq0\end{cases}\Rightarrow x\neq\pm7\\\\\frac{x+3}{x-7}-\frac6{x+7}-\frac{140}{(x-7)(x+7)}=0\\\frac{(x+3)(x+7)-6(x-7)-140}{(x-7)(x+7)}=0\\x^2+10x+21-6x+42-140=0\\x^2+4x-77=0\\D=16-4\cdot(-77)=16+308=324=(18)^2\\x_{1,2}=\frac{-4\pm18}2\\x_1=-11\\x_2=7\;-\;He\;nogx.\;no\;O.D.3.\\OTBET:\;x=-11$