Question

General term of a sequence is Tn=2n + 5, then Ts=​

Answer 1

Answer:

t_s = n^2 +6n

Step-by-step explanation:

t_s = \displaystyle \sum_1 ^n t_n

t_s = \displaystyle \sum_1 ^n 2n+5

t_s = \displaystyle \sum_1 ^n 2n + \displaystyle \sum_1 ^n 5

t_s = \displaystyle 2\sum_1 ^n n + 5 $\times$ n

t_s = 2{[n(n+1)]/2} + 5n

t_s = n^2 + n +5n

t_s = n^2 +6n