Question

S1=n
S2=2n
S3=3n
Prove that,
S3= 3(s2-s1)

Answer 1

we have

s1=n ---(1)

s2 = 2n --(2)

s3= 3n ---(3)

to prove

s3=3 (s2-s1)

LHS

S3 =3 n

s3 = 3 (2n - n)

from equation (1)and (2)

s3 = 3(s2-s1)

hence proved

Answer 2

It's your answer.....

It may help yuhhh.....