Find the range of .

MATHEMATICS · Single correct · AoPS · Mathematics · Special Functions · Special Functions

Problem

Find the range of

f(x)=4-2\,\mathrm{sgn}(x)

. (a)

\{2,6\}

(b)

\{2,4,6\}

(c)

\{4,6\}

(d)

\{2,4\}