Question

the sum of a term of an A.P is 3n² +n.​

Answer 1

Answer:

Step-by-step explanation:

A = 3+1=4

D = 2×3 = 6

Ap = 4,10,16,22... 6n-2

Answer 2

Step-by-step explanation:

Since S

n

=3n

2

−n and d=6

⇒S

n

=

2

n

(2a+(n−1)d)=3n

2

−n

2

n

(2a+(n−1)6)=3n

2

−n

n(a+(n−1)3)=3n

2

−n

(a+3n−3)=3n−1

a=2