Given the function `f(x)=(a^x+a^(-x))/2(w h e r ea >2)dotT h e nf(x+y) – InterviewSolution

1.	Given the function `f(x)=(a^x+a^(-x))/2(w h e r ea >2)dotT h e nf(x+y)+f(x-y)=``2f(x)dotf(y)`(b) `f(x)dotf(y)``(f(x))/(f(y))`(d) none of these
Answer» Correct Answer - A We have `f(x+y)=f(x-y)=(1)/(2)[a^(x+y)+a^(-x-y)+a^(x-y)+a^(-x+y)]` `=(1)/(2)[a^(x)(a^(y)+a^(-y))+a^(-x)(a^(y)+a^(-y))]` `=(1)/(2)(a^(x)+a^(-x))(a^(y)+a^(-y))=2f(x)f(y)`

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