Question

Determinati x∈Z astfel incat:
a) |x|<3
b) |x|<0
c) 3≤|x|≤5

Answer 1

a) |x|<3
-3<x<3
x∈Z⇒S:x∈{-2,-1,0,1,2}

b)|x|<0
Dar:|x|≥0 pentru orice x∈R.
S: ∅

c)3≤|x|≤5
i)3≤x≤5
x∈Z⇒x∈{3,4,5}
ii)-3≥x≥-5
x∈Z⇒x∈{-3,-4,-5}
S:x∈{-5,-4,-3,3,4,5}