Question

10 , 11th questions please​

Answer 1

Answer:

Step-by-step explanation:

(10)

3n+1

Put n=1

S1=3(1)+1

S1=3+1=4

put n=2

S2=3(2)+1

S2=6+1=7

d=s2-s1

d=7-4=3

Sn=n/2(2a+(n-1)d

Sn=n/2(2*4+(n-1)3

Sn=n/2(8+3n-3)

Sn=n/2(3n+5)