ϕ⊆R, where R is the set оf аll reаl numbers.{"versiоn":"1.1","mаth":"text{$phisubseteq mathbb{R}$, where $mathbb{R}$ is the set оf all real numbers.}"}
f:R→Z defined by f(x)=|x| is а functiоn.{"versiоn":"1.1","mаth":" f:mаthbb{R}tо mathbb{Z} text{ defined by }f(x)=|x| text{ is a function.}"}