$\Big(x^2+\dfrac{3}{x}\Big)^5$
$=C_5^0.x^{2.5}\dfrac{3^0}{x^0}+C_5^1.x^{2.4}\dfrac{3}{x}+C_5^2.x^{2.3}\dfrac{3^2}{x^2}+C_5^3.x^{2.2}\dfrac{3^3}{x^3}+C_5^4.x^{2.1}\dfrac{3^4}{x^4}+C_5^5.x^0.\dfrac{3^5}{x^5}$
$=x^{10}+15x^7+90x^4+270x+\dfrac{405}{x^2}+\dfrac{243}{x^5}$