大一经济学数学。。。。

Question

如题所述

Answer 1

(1)
lim(x->-2) (x^3+3x^2+2x)/(x^2-x-6)
=lim(x->-2) x(x+2)(x+1)/[(x+2)(x-3)]
=lim(x->-2) x(x+1)/(x-3)
=-2(-1)/(-5)
-2/5

(2)
lim(x->∞)[√(x^2+1) -√(x^2-1) ]
=lim(x->∞)[(x^2+1) -(x^2-1) ]/[√(x^2+1) +√(x^2-1) ]
=lim(x->∞) 2/[√(x^2+1) +√(x^2-1) ]
=0

(3)
lim(x->∞) (2x-3)^20 .(3x+5)^30 / (5x+1)^50
=lim(x->∞) (2-3/x)^20 .(3+5/x)^30 / (5+1/x)^50
=6/5

(4)
lim(x->∞)( x/(1+x))^x
=lim(x->∞)( 1- 1/(1+x))^x
= 1/e追问

谢谢大神！！！！！

Answer 2

那就删掉我的图了