Question

Every term of G.P. is positive and also every term is sum of two preceding terms. Then the common ratio of G.P. is

• A. $\frac { 1 - \sqrt { 5 } } { 2 }$
• B. $\frac { \sqrt { 5 } + 1 } { 2 }$
• C. $\frac { \sqrt { 5 } - 1 } { 2 }$
• D. None of these

Answer 1

Answer: (B)

$\frac { \sqrt { 5 } + 1 } { 2 }$

Answer 2

a, ar, ar²,…….

ar² = a + ar Ž r² – r – 1 = 0

r = $\frac { 1 \pm \sqrt { 5 } } { 2 }$ but r > 0 \ r = $\frac { 1 + \sqrt { 5 } } { 2 }$