Answer
The rational expression is proper.
Work Step by Step
The rational expression $\displaystyle \frac{P}{Q}$ is called proper if
the degree of the polynomial in the numerator is less than the degree of the polynomial in the denominator.
Otherwise, the rational expression is called improper.
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The degree of the numerator, $P(x)=5x+2$,
is $1$, and
the degree of the denominator$ , Q(x)=x^{3}-1$
is $3$.
The rational expression is proper.
