if Sn denoted sum to n terms of G.P. prove that (S10 - S20)2 = S10(S30 - S20)
As Sn is sum of n terms which is given by the formula
Sn=a(1-rn)/(1-r)
Where a is first term of GP and r is common ratio
We have to prove, (S10 - S20)2 = S10(S30 - S20)
Now LHS
(S10 - S20)2
=
Now RHS
= S10(S30 - S20)
=
LHS=RHS
Hence proved
Sn=a(1-rn)/(1-r)
Where a is first term of GP and r is common ratio
We have to prove, (S10 - S20)2 = S10(S30 - S20)
Now LHS
(S10 - S20)2
=
Now RHS
= S10(S30 - S20)
=
LHS=RHS
Hence proved