Which statement best describes how to determine whether f(x) = x4 – x3 is an even function? determine whether (–x)4 – (–x)3 is equivalent to x4 – x3. determine whether (–x4) – (–x3) is equivalent to x4 + x3. determine whether (–x)4 – (–x)3 is equivalent to –(x4 – x3). determine whether (–x4) – (–x3) is equivalent to –(x4 + x3).