Question

The first term & the last term of an arith
metic progression are a' & I respectively,
then the sum of its first n terms is
A) sn=n(2a+l)
B) sn = n(a+(n-1)d
C)sn= n(a+l)
D) sn = a(n+l)

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Answer 1

Step-by-step explanation:

The first term & the last term of an arith

metic progression are a' & I respectively,

then the sum of its first n terms is

A) sn=n(2a+l)

✍ ʜᴏᴘᴇ ɪᴛ's ʜᴇʟᴘғᴜʟ ᴛᴏ ʏᴏᴜ ✍

Answer 2

Answer:

Step-by-step explanation:

answer is n/2(a+l)

the proof of snth formula is given in picture i hope you like it