Answer: The required value of the radical is
![6\sqrt2.](https://img.qammunity.org/2020/formulas/mathematics/middle-school/f1hrzoef4ifvp27f1oo6usodp979s4pjei.png)
Step-by-step explanation: We are given to evaluate the following radical :
![R=3\sqrt 8.](https://img.qammunity.org/2020/formulas/mathematics/middle-school/yyumk820wj1yw8z5wd9ri5fwtw4p6h2rwx.png)
We will be using the following property of radicals :
For real numbers a and b, we have
![√(a* b)=\sqrt a* \sqrt b.](https://img.qammunity.org/2020/formulas/mathematics/middle-school/8ainf5j8bh8n6f6ad1xi5pwr2qcxs2nszj.png)
So,
![R\\\\=3\sqrt 8\\\\=3√(4* 2)\\\\=3* \sqrt 4* \sqrt 2\\\\=3* 2* \sqrt 2\\\\=6\sqrt 2.](https://img.qammunity.org/2020/formulas/mathematics/middle-school/i6mjyx6b19jn30jkbkhp1wet4sroqo82nw.png)
Thus, the required value of the given radical is
![6\sqrt2.](https://img.qammunity.org/2020/formulas/mathematics/middle-school/f1hrzoef4ifvp27f1oo6usodp979s4pjei.png)