Answer:
The product of two rational numbers is a rational number
Explanation:
I'll quickly recap the proof: a rational number is, by definition, the ratio between two integers. So, there exists four integers m,n,p,q such that
![a=(m)/(n),\quad b=(p)/(q)](https://img.qammunity.org/2020/formulas/mathematics/middle-school/1jzz38521n577utyw3amutkvvyf3nx4tgs.png)
If we multiply the fractions, we have
![ab = (mp)/(nq)](https://img.qammunity.org/2020/formulas/mathematics/middle-school/2nt1tylghu54m82zhb7z3sq8rlevei86nd.png)
Now, mp and nq are multiplication of integers, and thus they are integers themselves. So, ab is also a ratio between integer, and thus rational.