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Manipal MET2014MathematicsFunctions

If f(x)= a^x+a^ -x 2 and f(x+y)+f(x-y)=k f(x) f(y) , then k is equal to

Options

  1. A2
  2. B4
  3. C-2
  4. DNone of these

Correct answer

A. 2

Step-by-step solution

On putting y=0 , in the given relation, we get array ll f(x)+f(x)=k f(x) f(0) & & 2 f(x)=k f(x) & k=2 array [ f(0)=1]

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