Question

this problem can u solve it?​

Answer 1

Answer:

(C) 115

Step-by-step explanation:

tn = (1/n)(1+2+3...n)

tn= (1/n)[(n)(n+1)/2]

tn = (n+1)/2

now S = €[n+1]/2

S = 1/2 [(€n) + €n]

S = 1/2[(n)(n+1)/2 + n]

now n= 20

S = 1/2 [ (20×21/2) + 20]

S = 115

Note

€ means sigma (sum)

Answer 2

Answer:

Surely kab online aaoge?