Neither Odd Nor Even?

Algebra Level 3

How many function(s) with domain R \mathbb{R} and range R \subseteq \mathbb{R} are both even and odd?

Image Credit: Wikipedia Even and Odd Function
Infinitely many 2 1 0 Greater than 2

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1 solution

Steven Yuan
Mar 2, 2015

An even function satisfies

f ( x ) = f ( x ) f(-x) = f(x)

for all x x in the domain. An odd function satisfies

f ( x ) = f ( x ) f(-x) = -f(x)

for all x x in the domain. Thus, a function that is both even and odd must have

f ( x ) = f ( x ) . f(x) = -f(x).

The only function with range in the real numbers that satisfies this is f ( x ) = 0 f(x) = 0 , so there is only 1 \boxed{1} function.

Why did I think constant functions would satisfy the criteria? My mind's not working today. Anyhow, nice problem.

Jake Lai - 6 years, 3 months ago

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Constant functions except 0 , never be odd function :) .

Deepanshu Gupta - 6 years, 3 months ago

the function like ax²-by²=0 can be included? Because it is correct for the question , and the graph of it is like a big X and the centre of X is on origin , isn't it is a odd and even function?

Kelvin Hong - 5 years, 8 months ago

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That is not a Function . A function has to satisfy the vertical line test.

Calvin Lin Staff - 5 years, 8 months ago

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