a) \(\frac{2x-1}{x^2-5x+6}\)
\(=\frac{5x-10-3x+9}{x^2-2x-3x+6}\)
\(=\frac{5\left(x-2\right)-3\left(x-3\right)}{x\left(x-2\right)-3\left(x-2\right)}\)
\(=\frac{5\left(x-2\right)-3\left(x-3\right)}{\left(x-3\right)\left(x-2\right)}\)
\(=\frac{5\left(x-2\right)}{\left(x-3\right)\left(x-2\right)}\)\(-\frac{3\left(x-3\right)}{\left(x-3\right)\left(x-2\right)}\)
\(=\frac{5}{x-3}+\frac{-3}{x-2}\)