Is the function f(x) = x^3f(x)=x3 symmetric with respect to the y-axis?

1 Answer
Mar 18, 2018

No, it has rotational symmetry of order 22 about the origin.

Explanation:

  • An even function is a function satisfying:
    f(-x) = f(x)" "f(x)=f(x) for all xx in the domain of f(x)color(white)(0/0)f(x)00

  • An odd function is a function satisfying:
    f(-x) = -f(x)" "f(x)=f(x) for all xx in the domain of f(x)color(white)(0/0)f(x)00

Even functions are symmetric with respect to the yy-axis.

Odd functions have rotational symmetry of order 22 about the origin.

Given:

f(x) = x^3f(x)=x3

Note that for any value of xx:

f(-x) = (-x)^3 = (-1)^3 x^3 = -x^3 = -f(x)f(x)=(x)3=(1)3x3=x3=f(x)

So f(x) = x^3f(x)=x3 is an odd function.

It is not symmetric with respect to the yy-axis, but it has rotational symmetry of order 22 about the origin.

graph{x^3 [-5, 5, -10, 10]}

In fact any polynomial consisting of only terms of odd degree will be an odd function and any polynomial consisting of only terms of even degree will be an even function.