If the function f (x) = k − 2x1 + K · 2x (k is a constant) is odd in the domain of definition, then the value of K is______ .

If the function f (x) = k − 2x1 + K · 2x (k is a constant) is odd in the domain of definition, then the value of K is______ .

∵ function f (x) = k − 2x1 + K · 2x ∵ f (- x) = - f (x) ∵ K − 2 − X1 + K · 2 − x = − K − 2x1 + K · 2x ∵ (k2-1) (2x) 2 = 1-k2 ∵ (k2-1) = 0 ∵ k = ± 1, so the answer is: ± 1