a, \(\dfrac{-1}{2-3x}+\dfrac{5}{3x-2}=\dfrac{1}{3x-2}+\dfrac{5}{3x-2}=\dfrac{1+5}{3x-2}=\dfrac{6}{3x-2}\)
b, \(\dfrac{2a-1}{2a+1}-\dfrac{2a-3}{2a-1}=\dfrac{\left(2a-1\right)^2}{\left(2a-1\right)\left(2a+1\right)}-\dfrac{\left(2a-3\right)\left(2a+1\right)}{\left(2a-1\right)\left(2a+1\right)}\)
\(=\dfrac{4a^2-4a+1}{\left(2a-1\right)\left(2a+1\right)}-\dfrac{4a^2-4a-3}{\left(2a-1\right)\left(2a+1\right)}\)
\(=\dfrac{4a^2-4a+1-4a^2+4a+3}{\left(2a-1\right)\left(2a+1\right)}=\dfrac{4}{4a^2-1}\)
c, \(\dfrac{2}{x+3}+\dfrac{3}{x^2-9}=\dfrac{2\left(x-3\right)}{\left(x-3\right)\left(x+3\right)}+\dfrac{3}{\left(x-3\right)\left(x+3\right)}\)
\(=\dfrac{2x-6+3}{\left(x-3\right)\left(x+3\right)}=\dfrac{2x-3}{x^2-9}\)
