1+3+32+......+3n−1=3n−12
Find (33−23)+(53−43)+(73−63)+.... to 10 terms.
Or
Show that 1×22+2×32+....+n×(n+1)212×2+22×3+....+n2×(n+1)=3n+53n+1
1+3+32+⋯+3n−1=(3n−1)2
limx→∞(13+132+133+....+13n)