A) \[5\]
B) \[15\]
C) \[10\]
D) Both [a] and [b]
Correct Answer: D
Solution :
\[{{f}_{2}}(x)=f(f(x))=f(x)=x\] \[{{f}_{3}}(x)=f({{f}_{2}}(x))=f(x)=x\] \[\Rightarrow \]\[{{x}^{3}}-25{{x}^{2}}+175x-375=0\] \[(x-5)({{x}^{2}}-20x+75)=0\] \[{{(x-5)}^{2}}(x-15)=0\Rightarrow x=5,\,\,15\]You need to login to perform this action.
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