lim(x,y都趋向无穷大）x^2/2^x+y^2/2^y为什么为0?
问题描述：
lim(x,y都趋向无穷大）x^2/2^x+y^2/2^y为什么为0?
答
lim(x,y都趋向无穷大）x^2/2^x+y^2/2^y=limx^2/2^x+limy^2/2^y=lim[2x/(ln2*2^x)]+lim[2y/(ln2*2^y)]=lim2/[(in2)^2*2^x]+lim2/[(in2)^2*2^y]=0