2(x - 2)(x + 3)的渐近线求 f(x)=x-12(xF(x)lim=limf(x-ax)lima-x-→0X→士80X80Xf(x)2(x - 2)(x + 3)-2=a又: limlimx(x -1)X-→00xx->00lim[f(x) - ax] =lim[f(x) - 2x]x8x82(x - 2)(x + 3)-2xl= limx-1x-2(x - 2)(x + 3) - 2x(x -1):4=b= limx-1X→>00：J=2x+4是曲线的一条斜渐近线
= → x f x x ( ) 又lim ( 1) 2( 2)( 3) lim − − + → x x x x x = 2 2 ] 1 2( 2)( 3) lim[ x x x x x − − − + = → 1 2( 2)( 3) 2 ( 1) lim − − + − − = → x x x x x x = 4 y = 2x + 4是曲线的一条斜渐近线. = − − + → 1 2( 2)( 3) lim x x x x 无水平渐近线 − = → lim[ f (x) ax] x . 1 2( 2)( 3) 求 ( ) 的渐近线 − − + = x x x f x lim[ f (x) 2x] x − → b lim [ f (x) ax] x = − → , ( ) lim x f x a x→ = = a = b
习选择题：x曲线的渐近线,共有y:(x -1)(x-2)(D) 4条(A) 1条.(C) 3条.(B) 2条
曲线 的渐近线， ( 1)( 2) | | − − = x x x x y 共有 (B) (A) 选择题: 1条. 2条 (D) . (C) 3条. 4条