if tn=n/(n+1)! then Σ tn is equal to (where summation is from n=1 to n=20) Share with your friends Share 7 Lovina Kansal answered this Dear student ∑n=120tn=∑n=120nn+1!=∑n=120n+1-1n+1!=∑n=120n+1n+1!-1n+1!=∑n=120n+1(n+1)n!-1(n+1)!=∑n=1201n!-1n+1!=11-12!+12!-13!+....+119!-120!+120!-121!=1-121!≈1 Regards 24 View Full Answer