first off, we change the mixed fraction to "improper" and then we make it a decimal.
[tex]\bf \stackrel{mixed}{9\frac{3}{2}}\implies \cfrac{9\cdot 2+3}{2}\implies \stackrel{improper}{\cfrac{21}{2}}\implies 10.5 \ne \mathbb{Z}[/tex]
an integer is a "whole" number, with no decimals.