2极限运算法则,两个重要极限 设limf(x)=Aimg(x)=B,则 )lin[f(x)±g(x)]=lm/(x)±img(x)=A±B m0()g8)=[lm/(x)[mg() A·B. (3)若B≠0, limf(x)A lin lim B2.极限运算法则， 两个重要极限 设 则 lim ( ) ,lim ( ) , x x f x = A g x = B ⑴ lim ( ) ( ) ( lim ) lim ( ) . x x x ⎡ ⎤ f x ± g x = ± f x g x = A ± B ⎣ ⎦ ⑵ lim ( ) ( ) lim ( ) lim ( ) . x x x ⎡ ⎤ f x ⋅ g x = ⋅ ⎡ ⎤ f x ⎡ g x A ⎤ = ⋅ B ⎣ ⎦ ⎣ ⎦ ⎣ ⎦ ⑶ 若B ≠ 0, ( ) ( ) ( ) ( ) lim lim . lim x x x f x f x A g x g x B = =