Judge the parity of (1) f (x) = 1 / 2x. (2) f (x) = - 2x + 5. (3) f (x) = X4 + x2-1. (4) f (x) = 2x3-x By the way, write down its domain

Judge the parity of (1) f (x) = 1 / 2x. (2) f (x) = - 2x + 5. (3) f (x) = X4 + x2-1. (4) f (x) = 2x3-x By the way, write down its domain

All parity problems can be solved by definition method or equivalent transformation method
(1) F (- x) = - 1 / 2x = f (x), so it is an odd function and the domain of definition is x ∈ R
(2) F (- x) = 2x + 5, so it is neither odd nor even function, and the domain of definition is x ∈ R
(3) F (- x) = (- x) ^ 4 + (- x) ^ 2-1 = x ^ 4 + x ^ 2-1 = f (x), so it is even function, and the domain of definition is x ∈ R
(4) F (- x) = 2 (- x) ^ 3 - (- x) = - (2x ^ 3-x) = - f (x), so it is an odd function, and the domain of definition is x ∈ R