\(P=\left(\frac{x}{x^2-25}-\frac{x-5}{x^2+5x}\right):\frac{2x-5}{x^2+5x}+\frac{x}{5-x}\)
\(P=\left[\frac{x}{\left(x-5\right)\left(x+5\right)}-\frac{x-5}{x\left(x+5\right)}\right]:\frac{2x-5}{x\left(x+5\right)}+\frac{x}{5-x}\)
\(P=\frac{x^2-\left(x-5\right)\left(x-5\right)}{\left(x-5\right)\left(x+5\right)x}.\frac{x\left(x+5\right)}{2x-5}+\frac{x}{5-x}\)
\(P=\frac{x^2-x^2+10x-25}{x\left(x-5\right)\left(x+5\right)}.\frac{x\left(x+5\right)}{2x-5}+\frac{x}{5-x}\)
\(P=\frac{10x-25}{x\left(x-5\right)\left(x+5\right)}.\frac{x\left(x+5\right)}{2x-5}+\frac{x}{5-x}\)
\(P=\frac{5\left(2x-5\right).x\left(x+5\right)}{x\left(x-5\right)\left(x+5\right)\left(2x-5\right)}+\frac{x}{5-x}\)
\(P=\frac{5}{x-5}+\frac{x}{5-x}\)
\(P=\frac{5}{x-5}-\frac{x}{x-5}\)
\(P=\frac{5-x}{x-5}\)
\(P=\frac{-\left(x-5\right)}{x-5}\)
\(P=-1\)
=> Giá trị của biểu thức P không phụ thuộc vào biến
đpcm
