If a, b, c, and d are in G. P., then (a+b)2 , (b+c)2 , and (c+d)2 are also in G. P.
True
Since a, b, c, and d are in G. P
∴ ba = ab = dc
∴ b2 = ac, c2 = bd, ad = bc ...........(1)
Now, (a+b)2×(c+d)2 = (ac+bc+ad+bd)2
= (b2+c2+2bc)2 ...[Using (1)]
= ((b+c)2)2
∴ (c+d)2(b+c)2 = (b+c)2(a+b)2
Thus, (a+b)2,(b+c)2,(c+d)2 are in G. P