If f (x) = 1-х, which value is equivalent to |f (i) |?

We have to determine which value is equivalent to | f (i) | if the function is: f (x) = 1 - x. So we know that : z = a + b i, the absolute value is: | z | = sqrt (a^2 + b^2). In this case: | f (i) | = | 1 - i |. So: a = 1, b = - 1. | f (i) | = sqrt (1^2 + ( - 1) ^2) = sqrt (1 + 1) = sqrt (2). Answer: C. sqrt (2)