Answer
1/(7x); x cannot equal 0
Work Step by Step
Recall, if two exponents with the same base (in this case, x) are in the numerator and the denominator of a fraction, we subtract the exponent in the numerator by the exponent in the denominator of the fraction. Thus, we obtain:
$ 4x^{3} / 28x^{4} \\\\ 4 / 28 x \\\\1/7x$
x cannot equal 0, for if x equaled 0, then the denominator of the original fraction would simplify to 0, which is not allowed.
