Question

If the function f:R->R defined by f(x) = 3^x+3^-x/2,then show that f(x+y)+f(x-y)=2f(x)f(y)

Answer 1

function f : R→R satisfies the equation f(x)f(y) - f(xy) = x + y ∀ x, y ∈ R and f (1)>0, then