Identify the roots of the function g (x) = x^2 - 8x + 16

A function is not this but for example g times x is

A function doesn't have roots until you give it a numerical value.

Then, the roots are the values of the variable that give the function

that value.

For example, if you said that g (x) = 0,

then the roots would both be x = 4.

But if you said that g (x) = 16, then

the roots would be x=0 and x=8.