Question

The nth term of an AP is 3+2n. What is the sum of its first seven terms?​

Answer 1

a1 = 3+2(1) =5

a2 = 3+2(2) = 7

a3 = 3+2(3) =9

AP : 5,7,9,...

d = a2 - a1 = 7 - 5 = 2

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

S7 = 7/2 [ 2×5 + (7-1) × 2]

= 7/2 [ 10 + 6×2 ]

= 7/2 [ 10+12 ]

= 7/2 [ 22 ]

= 7×11

=77

Answer 2

Answer:

ᴡᴏʜ ᴀᴘᴋɪ ᴛʜɪɴᴋɪɴɢ ᴘᴇ ᴅᴇᴘᴇɴᴅ ʜᴀɪ

Step-by-step explanation:

ᴍᴜᴊʜᴇ ɴʜɪ ᴘᴀᴛᴀ ᴀᴀᴘ ᴋᴀɪsᴇ ʟᴀʀᴋɪ ʜᴏ