A) 3
B) \[\frac{1}{2}\]
C) 2
D) \[\frac{1}{3}\]
Correct Answer: A
Solution :
\[3+x,\ 9+x,\ 21+x\] are in G.P. \[\Rightarrow \] \[{{(9+x)}^{2}}=(3+x)(21+x)\] \[\Rightarrow \] \[81+{{x}^{2}}+18x={{x}^{2}}+24x+63\] \[\Rightarrow \] \[6x=18\] or \[x=3\]. Trick: Check for (a), \[3+3,\ 9+3,\ 21+3\] are in G.P.
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