lim(n→∞)(n+1)/(3n-1)=lim(n→∞)(1+1/n)/(3-1/n)=1/3
证明:
任取ε>0
由|(n+1)/(3n-1)-1/3|=4/[3(3n-1)|=4/(9n-3)4/(9ε)+1/3
取N=[4/(9ε)+1/3]+1,则当n>N时,|(n+1)/(3n-1)-1/3|
lim(n→∞)(n+1)/(3n-1)=lim(n→∞)(1+1/n)/(3-1/n)=1/3
证明:
任取ε>0
由|(n+1)/(3n-1)-1/3|=4/[3(3n-1)|=4/(9n-3)4/(9ε)+1/3
取N=[4/(9ε)+1/3]+1,则当n>N时,|(n+1)/(3n-1)-1/3|