(1)lim(n→∞)[(1+3分之1+9分之1+.+(3n)分之1}
(1+3分之1+9分之1+.+(3n)分之1}=[1-(1/3)^(n+1)]/(1-1/3)=(3/2)*[1-(1/3)^(n+1)]
∴ lim(n→∞)[(1+3分之1+9分之1+.+(3n)分之1}
= lim(n→∞)(3/2)*[1-(1/3)^(n+1)]
=3/2
(1)lim(n→∞)[(1+3分之1+9分之1+.+(3n)分之1}
(1+3分之1+9分之1+.+(3n)分之1}=[1-(1/3)^(n+1)]/(1-1/3)=(3/2)*[1-(1/3)^(n+1)]
∴ lim(n→∞)[(1+3分之1+9分之1+.+(3n)分之1}
= lim(n→∞)(3/2)*[1-(1/3)^(n+1)]
=3/2