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If a, b, c are in G.P., prove that : (a2 + b2), (b2 + c2), (c2 + d2) are in G.P. |
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Answer» a, b, c, d are in G.P. Therefore, bc = ad … (1) b2 = ac … (2) c2 = bd … (3) To prove: (a2 + b2), (b2 + c2), (c2 + d2) are in G.P, we need to prove that: (a2 + b2) (c2 + d2) = (b2 + c2)2 {deduced using GM relation} ∴ RHS = (b2 + c2)2 = b4 + c4 + 2b2c2 = a2c2 + b2d2 + a2d2 + b2c2 {using equation 2 and 3} = c2(a2 + b2) + d2(a2 + b2) = (a2 + b2) (c2 + d2) = LHS ∴ (a2 + b2), (b2 + c2), (c2 + d2) are in G.P Hence proved. |
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