ï¼4ï¼è§£ï¼åå¼=lim(x->â)[(3-1/x)^25*(2-1/x)^20/(2+1/x)^45] (åååæ¯åé¤x^45)
=(3-0)^25*(2-0)^20/(2+0)^45=(3/2)^25ï¼
ï¼5ï¼è§£ï¼åå¼=lim(x->1)[(-(1-x)(x+2))/((1-x)(1+x+x^2))] (éåååç®)
=lim(x->1)[-(x+2)/(1+x+x^2)] (åååæ¯åé¤(1-x))
=-(1+2)/(1+1+1^2)=-1;
ï¼6ï¼è§£ï¼åå¼=lim(x->â)[2/(â(x^2+1)+â(x^2-1))]
(åååæ¯åä¹(â(x^2+1)+â(x^2-1)))
=lim(x->â)[(2/x)/(â(1+1/x^2)+â(1-1/x^2))] (åååæ¯åé¤x)
=0/(â(1+0)+â(1-0))=0ï¼
ï¼8ï¼è§£ï¼åå¼=lim(n->â)[((1+2/n)^3+(2+3/n)^3)/((1-1/n)(2-1/n)(3-2/n))]
(åååæ¯åé¤n^3)
=((1+0)^3+(2+0)^3)/((1-0)(2-0)(3-0))=3/2ã
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