a: \(\dfrac{x}{2x^2+7x-15}=\dfrac{x}{2x^2+10x-3x-15}=\dfrac{x}{\left(x+5\right)\left(2x-3\right)}=\dfrac{x\left(x-2\right)}{\left(x+5\right)\left(x-2\right)\left(2x-3\right)}\)
\(\dfrac{x+2}{x^2+3x-10}=\dfrac{x+2}{\left(x+5\right)\left(x-2\right)}=\dfrac{\left(x+2\right)\left(2x-3\right)}{\left(x+5\right)\left(x-2\right)\left(2x-3\right)}\)
\(\dfrac{1}{x+5}=\dfrac{\left(2x-3\right)\left(x-2\right)}{\left(x+5\right)\left(x-2\right)\left(2x-3\right)}\)