Question

The sum of n terms of an A.P. is 3N^2, the term which equal 159 is
13
21
27
NONE OF THESE

Answer 1

27 ɪs ᴛʜᴇ ʀɪɢʜᴛ ᴀɴsᴡᴇʀ

ʜᴏᴘᴇ ɪᴛ ɪs ʜᴇʟᴘғᴜʟ ғᴏʀ ʏᴏᴜ!!

Answer 2

Tn=Sn-(Sn-1)

Tn=159

Sn=3n^2+5

Sn-1=3(n-1)^2+5

Sn-1=3(n^2–2n+1)+5

Sn-1=3n^2–6n+3+5

Sn-1=3n^2–6n+8

Substituting the values in the first eqn

159=3n^2+5-(3n^2–6n+8)

159=3n^2+5–3n^2+6n-8

159=6n-3

159+3=6n

6n=162

N=27

Your answer is 27th value

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