Question

Dau coroana *
det.nr.naturale care verifica inegalitatile:
11≤ x+3≤17
5≤ x-1≤9
det.nr.naturale care verifica relatiile :
x+7≤35 si x≥23
210+x<1210 si x>997

Answer 1

11≤x+3≤17
atunci x+3∈{12,13,..16}
x+3=17
x=17-3
x=14

x+3=11             
x=11-3=8
=>x∈{8,9,..14}
**5<x-1<9
atunci x-1∈{6,7,8}
x-1=5
x=5+1
x=6
x-1=9
x=9+1
x=10
x∈{6,7..10}
***x+7≤35 si x≥23
x+7≤35
x≤35-7
x≤28
x∈{0,1,2..27}
****210+x<1210 si x>997 ,inseamna ca x trebuie sa fie mai mare decat 997 
210+x<1210-210
x<1000
x∈{998;999}