For this case we have:
Be a function of the form [tex]y = f (x)[/tex]
Where:
[tex]f (x) = \sqrt {x-5}[/tex]
If we want to find f (-2), we substitute [tex]x = -2[/tex], then:
[tex]f (-2) = \sqrt {-2-5}\\f (-2) = \sqrt {-7}[/tex]
Since we have a negative root, the result will be given by complex numbers. By definition:
[tex]\sqrt {-1} = i[/tex]
So:
[tex]f (-2) = \sqrt {7} i[/tex]
Answer:
[tex]f (-2) = \sqrt {7} i[/tex]
