Question
If a, b, c, d are in GP., show that (a2 + b2 + c2) (b2 + c2 + d2) = (ab + bc + cd)2
Solution
Here, a, b, c, d are in G.P. Let r be the common ratio of the G.P.
∴ b = ar, c = ar2, d = ar3
Now,
if
or if
or if
or if
which is true.
Hence, if a, b, c d are in G.P. then