\(A=1+\frac{3}{m-1}\cdot\sqrt{m^2-4m+4}\)
\(=1+\frac{3}{m-1}\cdot\sqrt{\left(x-2\right)^2}\)
\(=1+\frac{3}{m-1}\cdot\left|x-2\right|\)
\(=\frac{m-1}{m-1}+\frac{3\left(m-2\right)}{m-1}\)
\(=\frac{4m-7}{m-1}\)
\(B=\sqrt{1-10x+25x^2}-4x\)
\(=\sqrt{\left(5x-1\right)^2}-4x\)
\(=\left|5x-1\right|-4x\)