Question

求大神啊，，！！！！

Answer 1

(1)
lim(x->∞) (1+x+3x^2)/(x^2-2x-3)
分子分母同时除以x^2
=lim(x->∞) (1/x^2+1/x+ 3)/(1-2/x-3/x^2)
= 3
(2)
lim(x->∞) (1+x^2-x^3)/(6x^3-2x^2-3)
分子分母同时除以x^3
=lim(x->∞) (1/x^3+1/x-1)/(6-2/x-3/x^3)
=-1/6
(3)
let
3/x = 1/y
lim(x->∞) ( 1+3/x) ^(2x)
=lim(y->∞) ( 1+1/y) ^(6y)
=e^6
(4)
let
1/y = 1/(2x)
lim(x->∞) [ 1-1/(2x) ] ^(3x)
=lim(y->∞) ( 1-1/y) ^(3y/2)
=e^(-3/2)
(5)
lim(x->0) sin6x/x
=lim(x->0) 6x/x
=6
(7)
|sinx|≤1
lim(x->∞) (1+3x^2)/(x^3-2x+3) =0
=>
lim(x->∞) (1+3x^2).sinx/(x^3-2x+3) =0

Answer 2

求助大神，啊，那个郭德纲，这是什么歌？谢谢

Answer 3

Answer 4

这题并不难，我有忙待会给你答案。

Answer 5

头疼的高数 早忘玩了