求n→∞lim(3n³+2n²+1)/(2n²+3)
解一：原式=n→∞lim(3n+2+1/n²)/(2+3/n²)=∞
解二：原式=n→∞lim(9n²+4n)/(4n)=n→∞lim[(18n+4)/4]=n→∞lim[(9/2)n+1]=∞