Question

the nth term of an ap is represented by an= 3n+1. find the ap and the sum of first 20 terms of the ap​

Answer 1

Answer:

$8 \times \frac{ \times 7}{5 \times \frac{20}{3} }$

Answer 2

Answer:

A.P.=4,7,10,...

S20=650

Step-by-step explanation:

an=3n+1

when n=1, when n=2, when n=3,

a=3×1+1 a=3×2+1 a=3×3+1

a=4 a=7 a=10

A.P.=4,7,10,...

For finding sum,

a20=3×20+1

a20=61

a20=l

l=61 ,n=20 ,a=4

Sn=n/2(a+l)

S20=20/2(4+61)

S20=10×65

S20=650