、求极限方法举例 例1求lim →2x2-3x+5 A.. lim(x2-3x+5)=limx'-lim3x+lim5 x→)2 (lim x)'-3limx+lim 5 2 →2 →2 =22-3.2+5=3≠0, limx'-lim1 23-17 ∴皿x2-3+5Hm(x2-3+5 2 2 33 x→2 上一页下一页现回例1 . 3 5 1 lim 2 3 2 − + − → x x x x 求 解 lim( 3 5) 2 2 − + → x x x  lim lim3 lim5 2 2 2 →2 → → = − + x x x x x (lim ) 3lim lim5 2 2 2 →2 → → = − + x x x x x 2 3 2 5 2 = −  + = 3  0, 3 5 1 lim 2 3 2 − + −  → x x x x lim( 3 5) lim lim1 2 2 2 3 2 − + − = → → → x x x x x x . 3 7 = 3 2 1 3 − = 三、求极限方法举例