\(\left(\dfrac{a}{a-2}+\dfrac{a+2}{a^2-4}\right).\left(a-2\right)\)
\(=\left[\dfrac{a\left(a+2\right)}{a^2-4}+\dfrac{a+2}{a^2-4}\right].\left(a-2\right)\)
\(=\left[\dfrac{a\left(a+2\right)+\left(a+2\right)}{a^2-4}\right]\left(a-2\right)\)
\(=\left[\dfrac{\left(a+1\right)\left(a+2\right)}{a^2-4}\right]\left(a-2\right)\)
\(=\dfrac{a+1}{a-2}.\left(a-2\right)\)
\(=a+1\)