Question
A real valued function f(x) satisfies the functional equation f(x – y) = f(x) f(y) – f(a – x) f(a + y) where a is a given constant and f(0) = 1, f(2a – x) is equal to
-
–f(x)
-
f(x)
-
f(a) + f(a – x)
-
f(-x)
Solution
A.
–f(x)
f(a – (x – a)) = f(a) f(x – a) – f(0) f(x)
= - f(x) [ ∵ x = 0, y= 0, f(0) = f2 (0)-f2(a) = 0 ⇒ f(a) = 0]