例1:求下列极限 3n-2 Im (2) lir n> n n 2n2+n 3n3+n B3)lim (4) lim n→>3n2+2 n→2n+-n 2 2 解1)im(2+-)=1m2+lm==0+2lm==0+0=0 n→>00 n→00 3n-2 (2)lim-=limB3-=lim 3-lil n→>00 n→ n→00 n→00 3-2lm-=3-0=3 n 2o n2 2 1 2 1 2 2 (1) lim( ) lim lim 0 2lim 0 0 0 n n n n → → → → n n n n n 解： + = + = + = + = 3 2 2 2 (2) lim lim(3 ) lim 3 lim 1 3 2lim 3 0 3 n n n n n n n n n n → → → → →  − = − = − = − = − = 9 例1：求下列极限 2 1 2 (1) lim( ) n→ n n + 3 2 (2) lim n n → n − 2 2 2 (3) lim n 3 2 n n → n + + 3 4 2 3 (4) lim n 2 n n → n n + −