[tex]\left(\dfrac{2}{5}a^2x\right)\left(-\dfrac{1}{5}x^2a\right)=\left(\dfrac{2}{5}\right)\left(-\dfrac{1}{5}\right)(a^2xx^2a)=-\dfrac{2}{25}a^{2+1}x^{1+2}\\\\=\boxed{-\dfrac{2}{25}a^3x^3}[/tex]
