Question

The sum of 15 terms of arithmetic sequence 3,6,9,12…

Answer 1

Answer:

45

Step-by-step explanation:

an = a +(n-1)d

an= 3 + (15-1)3

an= 3+14*3

an= 3+42

an= 45

I hope the answer is right

Answer 2

Please mark my answer as brainliest.

ᴀᴩ =3,6,9,12 ...

a = 3 , d=3, n=15 , an =? , Sn =?

an = a+(n-1)d

an = 3+(15-1)3

an= 3+ 42

an= 45

Sn = n/2 (a+an)

Sn = 15/2 × (3+45)

Sn= 15/2 × 48

Sn = 15×24

Sn = 360

Hope it helps you !