\(=\dfrac{a^2+b^2}{a}+b:\dfrac{a^2+b^2}{a^2b^2}\cdot\dfrac{a^2+b^2}{a^3+b^3}\)
\(=\dfrac{a^2+b^2}{a}+b\cdot\dfrac{a^2b^2}{a^2+b^2}\cdot\dfrac{a^2+b^2}{a^3+b^3}\)
\(=\dfrac{a^2+b^2}{a}+\dfrac{a^2b^3}{a^3+b^3}\)
\(=\dfrac{a^5+a^2b^3+a^3b^2+b^5+a^3b^3}{a\left(a^3+b^3\right)}\)