Answer: The rational expression below is undefined when x is equal +5 and -5.
Step-by-step explanation: The rational expression will be undefined when the denominator is equal to zero. So, first you have to take the denominator and make it equal to zero.
![3x^(2) -75=0\\](https://img.qammunity.org/2021/formulas/mathematics/middle-school/fcvguiefyetgilqncipyukalptnlmp2pwj.png)
Then you divide the whole thing by three to get this:
![x^(2) -25=0](https://img.qammunity.org/2021/formulas/mathematics/middle-school/ltvtaxlrr2mko579l6ommkuv90ep07pak1.png)
Now you move 25 over to the other side of the equation and take the square-root of both sides.
![x^(2) =25\\x= +/- √(25)](https://img.qammunity.org/2021/formulas/mathematics/middle-school/r59i1n2q5pqmb4ljevbsw3n4315w4cc0ei.png)
Since the square root of 25 is equal to five. We know that the rational expression will be undefined when x= -5 and +5