Question

find the sum of first 20 term of statue arethamatic series 2+7+12using suitable formula ​

Answer 1

ɴᴏᴡ ᴡᴇ ᴋɴᴏᴡ ᴛʜᴀᴛ.

sɴ = [2ᴀ + (ɴ-1)ᴅ]

=> sɴ = [2*2 + (20-1)5] => sɴ = 10[4 + 19*5] =>sɴ = 10(4 + 95) =>sɴ = 10 * 99. => sɴ = 990.

ʜᴇɴᴄᴇ ᴛʜᴇ sᴜᴍ ᴏғ 20 ᴛᴇʀᴍs ᴏғ ᴛʜᴇ ᴀᴘ ɪs 990.

ʀᴇᴍᴇᴍʙᴇʀ.

1)sɴ = [2ᴀ + (ɴ-1)ᴅ] -ғᴏʀ ғɪɴᴅɪɴɢ sᴜᴍ ᴛɪʟʟ ɴᴛʜ ᴛᴇʀᴍ ᴏғ ᴀɴ ᴀᴘ. 2)ᴀɴ = 2ᴀ + {ɴ-1}ᴅ. -ғᴏʀ ғɪɴᴅɪɴɢ ɴᴛʜ ᴛᴇʀᴍ ᴏғ ᴀɴ ᴀᴘ.

ʜᴏᴘᴇ ᴛʜɪs ᴡɪʟʟ ʜᴇʟᴘ ᴜ ᴅᴇᴀʀ......