若对任意的正整数n,xn

问题描述:

若对任意的正整数n,xn

应该是0,由lim(n趋近于无穷)(zn-xn)=0可知lim(n趋近于无穷)zn=lim(n趋近于无穷)xn,由夹逼定理有lim(n趋近于无穷)yn=lim(n趋近于无穷)zn=lim(n趋近于无穷)xn,所以lim(n趋近于无穷)(zn-yn)=0

0因为yn≤zn,所以zn-yn≥0,所以lim(n→∞)(zn-yn)≥0因为xn≤yn,所以xn-yn≤0,所以lim(n→∞)(xn-yn)≤0因为lim(n→∞)(zn-xn)=0,所以lim(n→∞)(zn-yn)=lim(n→∞)[(zn-xn)+(xn-yn)]=lim(n→∞)(zn-xn)+lim(n→∞)(...