\(A=\left(\dfrac{x}{x^2-49}-\dfrac{x-7}{x^2+7x}\right):\dfrac{2x-7}{x^2+7x}+\dfrac{x}{7-x}\)
\(A=\left(\dfrac{x}{\left(x-7\right)\left(x+7\right)}-\dfrac{x-7}{x\left(x+7\right)}\right):\dfrac{2x-7}{x^2+7x}+\dfrac{x}{7-x}\)
\(A=\dfrac{x^2-\left(x-7\right)^2}{x\left(x-7\right)\left(x+7\right)}\times\dfrac{x^2+7x}{2x-7}+\dfrac{x}{7-x}\)
\(A=\dfrac{x^2-x^2+14x-49}{x\left(x-7\right)\left(x+7\right)}\times\dfrac{x\left(x+7\right)}{2x-7}+\dfrac{x}{7-x}\)
\(A=\dfrac{7\left(2x-7\right)}{x\left(x-7\right)\left(x+7\right)}\times\dfrac{x\left(x+7\right)}{2x-7}+\dfrac{x}{7-x}\)
\(A=\dfrac{7}{x-7}-\dfrac{x}{x-7}\)
\(A=\dfrac{7-x}{x-7}\)
\(A=-\dfrac{7-x}{7-x}\)
\(A=-1\)
\(A=\left(\dfrac{x}{x^2-49}-\dfrac{x-7}{x^2+7x}\right):\dfrac{2x-7}{x^2+7x}+\dfrac{x}{7-x}\)
\(A=\left(\dfrac{x}{\left(x-7\right)\left(x+7\right)}-\dfrac{x-7}{x\left(x+7\right)}\right).\dfrac{x^2+7x}{2x-7}-\dfrac{x}{x-7}\)
\(A=\dfrac{x^2-\left(x-7\right)^2}{x\left(x-7\right)\left(x+7\right)}.\dfrac{x\left(x+7\right)}{2x-7}-\dfrac{x}{x-7}\)
\(A=\dfrac{\left(x-x+7\right)\left(x+x-7\right)}{x-7}.\dfrac{1}{2x-7}-\dfrac{x}{x-7}\)
\(A=\dfrac{\left(x-x+7\right)\left(2x-7\right)}{x-7}.\dfrac{1}{2x-7}-\dfrac{x}{x-7}\)
\(A=\dfrac{7}{x-7}-\dfrac{x}{x-7}\)
\(A=\dfrac{7-x}{x-7}=\dfrac{-\left(x-7\right)}{x-7}=-1\)
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