The sqrt(7) part makes it irrational, so the answer is irrational.
Answer
[tex] -2\sqrt 7 [/tex] [tex]\text {is an irrational number}[/tex]
Explanation
[tex] -2\sqrt 7 [/tex] is an irrational number, an irrational number is a number that contains repeating decimals or that cannot be written as a simple fraction.