今求极限举例 例1求lim(2x-1) x→ Hif lim(2x-1)=lim 2x-lim 1-2 lim x-1-21-1=1 讨论若 P(x)=aorn+a1rn-l+..xxd Dl D/x-9 x→)x 提示mP(x)=P(x) x→x 例2求lim-x x2x2-5x+3 lim(x3-1) 解 2 23-1 x→)2x2-5x+3li(x2-5x+3)22-10+33 x→ 上页返回 结束 铃首页 上页 返回 下页 结束 铃 ❖求极限举例 •讨论 •提示 例 1 求 lim (2 1) 1 − → x x 例1  解 下页 若 n n P(x)=a0 x n +a1 x n−1 +  +a −1 x+a  则 lim ( ) ? 0 = → P x x x lim ( ) ( )0 0 P x P x x x = → >>>  解 lim( 5 3) lim( 1) 5 3 1 lim 2 2 3 2 2 3 2 − + − = − + − → → → x x x x x x x x x 3 7 2 10 3 2 1 2 3 =− − + − =  例 2 求 5 3 1 lim 2 3 2 − + − → x x x x 例2  解 解  lim( 5 3) lim( 1) 5 3 1 lim 2 2 3 2 2 3 2 − + − = − + − → → → x x x x x x x x x 3 7 2 10 3 2 1 2 3 =− − + − =  提问 lim (2 1) lim 2 lim 1 2 lim 1 2 1 1 1 1 1 1 1 − = − = − =  − = → → → → x x x x x x x lim (2 1) lim 2 lim 1 2 lim 1 2 1 1 1 1 1 1 1 − = − = − =  − = → → → → x x x x x x x lim (2 1) lim 2 lim 1 2 lim 1 2 1 1 1 1 1 1 1 − = − = − =  − = → → → → x x x x x x x lim (2 1) lim 2 lim 1 2 lim 1 2 1 1 1 1 1 1 1 − = − = − =  − = → → → → x x x x x x x 