\(A=\left(\frac{x+1}{x}\right)^2:\left[\frac{x^2+1}{x^2}+\frac{2}{x+1}\cdot\frac{x+1}{x}\right]\)
\(A=\left(\frac{x+1}{x}\right)^2:\left[\frac{x^2+1}{x^2}+\frac{2}{x}\right]\)
\(A=\left(\frac{x+1}{x}\right)^2:\left(\frac{x^2+1+2x}{x^2}\right)\)
\(A=\left(\frac{x+1}{x}\right)^2:\left(\frac{x+1}{x}\right)^2=1\)