if a,b,c,d are in G.P then the value of (a^2 + b^2 + c^2)(b^2 + c^2 + d^2) is: 1.(ab + ac + bc)^2 2.(ac + cd + ad)^2 3.(ab + bc + cd)^2 4.(ab + bc + ad)^2
Not so Max!
(a^2 + b^2 + c^2)(b^2 + c^2 + d^2) will have a term b^4 and a term c^4
In general (ab + bc + cd)^2 won't have. (The terms will only be equivalent under certain conditions).
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I believe it C
(a^2 + b^2 + c^2)(b^2 + c^2 + d^2) always equals (ab + bc + cd)^2
In GP or not in GP does not matter.
3. (ab + bc + cd)^2
+8 
