Which statement best describes how to determine whether [tex]\( f(x) = x^4 - x^3 \)[/tex] is an even function?

A. Determine whether [tex]\( (-x)^4 - (-x)^3 \)[/tex] is equivalent to [tex]\( x^4 - x^3 \)[/tex].
B. Determine whether [tex]\( (-x)^4 - (-x)^3 \)[/tex] is equivalent to [tex]\( -\left(x^4 - x^3\right) \)[/tex].
C. Determine whether [tex]\( \left(-x^4\right) - \left(-x^3\right) \)[/tex] is equivalent to [tex]\( x^4 + x^3 \)[/tex].
D. Determine whether [tex]\( \left(-x^4\right) - \left(-x^3\right) \)[/tex] is equivalent to [tex]\( -\left(x^4 + x^3\right) \)[/tex].



Answer :

To determine whether the function [tex]\( f(x) = x^4 - x^3 \)[/tex] is an even function, we need to verify if [tex]\( f(-x) = f(x) \)[/tex]. Let's proceed step-by-step:

1. Substitute [tex]\( -x \)[/tex] into the function:
[tex]\[ f(-x) = (-x)^4 - (-x)^3 \][/tex]

2. Simplify the expression:
[tex]\[ (-x)^4 = x^4 \quad \text{because} \quad (-x)^4 = (-x)(-x)(-x)(-x) = x^4 \][/tex]
[tex]\[ (-x)^3 = -x^3 \quad \text{because} \quad (-x)^3 = (-x)(-x)(-x) = -x^3 \][/tex]
[tex]\[ f(-x) = x^4 - (-x^3) = x^4 + x^3 \][/tex]

3. Compare [tex]\( f(-x) \)[/tex] to [tex]\( f(x) \)[/tex]:
[tex]\[ f(x) = x^4 - x^3 \][/tex]
[tex]\[ f(-x) = x^4 + x^3 \][/tex]

By comparing the original function [tex]\( f(x) = x^4 - x^3 \)[/tex] with [tex]\( f(-x) = x^4 + x^3 \)[/tex], we see that [tex]\( f(-x) \)[/tex] is not identical to [tex]\( f(x) \)[/tex].

Therefore, [tex]\( f(x) = x^4 - x^3 \)[/tex] is not an even function.

Considering the provided statements, the correct one that describes the process to determine whether [tex]\( f(x) = x^4 - x^3 \)[/tex] is an even function is:

Determine whether [tex]\( (-x)^4 - (-x)^3 \)[/tex] is equivalent to [tex]\( x^4 - x^3 \)[/tex].

Based on our calculations, the answer is False, so the function is not even.