Primul exercitiu:(adica 6)
A={x∈N /3<x+2≤5}
3<x+2≤5 /-2
1<x≤3
x∈{2,3}
A={2,3}
B={x∈N / 5≤2x+3<11}
5≤2x+3<11/-3
2≤2x<8/:2
1≤x<4
x∈{1,2,3}
B={1,2,3}
C={x∈N / 8<3x+2≤14}
8<3x+2≤14/-2
6<3x≤12/:3
2<x≤4
x∈{3,4}
C={3,4}
A∪B∪C={2,3}∪{1,2,3}∪{3,4}={1,2,3,4}
restu nu mai stiu,sorry :(((
