Question

if Sn,denotes the sum of an A.P,prove that S12=3(S8-S4)

Answer 1

given that S12 =3 (S8-S4)
=n/2*(2a+11d)=3 (n/2*(2a+7d)-n/2*(2a+3d)
2a+11d==3 (2a+7d-2a-3d)
2a+11d=3 (4d)
2a+11d=12d
2a=d.

the above equation satisfies only when the 1st term is half of the common difference.

:-)hope it helps u.

Answer 2

Answer:

Step-by-step explanation:

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