Răspuns :
a) A U B = { a,b,c,d}, A intersectat B = { b,c}, A-B ={a}, B - A = { d}
b) A U B ={1,2,3,4,5,6}, A inters. B ={ 2}, A - B ={3,4}, B - A ={5,6}
c) A U B={1,2,3,4,5,6,7,8,10}, A inters. B ={Ф}, multimea vida, A - B ={2,4,6,8,10}, B - A ={1,3,5,7}
d) se rezolva inecuatiile pt multimea A si B
pt. multimea A, Inecuatia 5x - 1 ≤ 24 ⇔ 5x ≤ 24 + 1 ⇔ 5x ≤ 25 ⇔
x ≤ 25/5 ⇔ x ≤ 5, x ∈ ( - 00, 5], deci
x ∈ N si x ∈( - 00, 5} ⇒ x ∈{ 0,1,2,3,4,5}, deci multimea A este
A = { 0,1,2,3,4,5}
pt. multimea B, inecuatia 3x + 1< 15⇔3x < 15 - 1⇔ 3x < 14⇒ x< 14/3⇒
x ∈ ( - 00, 14/3) si x ∈ N ⇒ x ∈ { 0,1,2,3,4}, doar nr/ naturale 14:3 =4,6⇒ deci se iau nr. pana la 4
B={0,1,2,3,4,5} si A =0,1,2,3,4,5,}⇒ A = B ={0,1,2,3,4,5}
A U B= {0,1,2,3,4,5}, A inters. B = {Ф}, A- B ={Ф}, B - A ={Ф"
b) A U B ={1,2,3,4,5,6}, A inters. B ={ 2}, A - B ={3,4}, B - A ={5,6}
c) A U B={1,2,3,4,5,6,7,8,10}, A inters. B ={Ф}, multimea vida, A - B ={2,4,6,8,10}, B - A ={1,3,5,7}
d) se rezolva inecuatiile pt multimea A si B
pt. multimea A, Inecuatia 5x - 1 ≤ 24 ⇔ 5x ≤ 24 + 1 ⇔ 5x ≤ 25 ⇔
x ≤ 25/5 ⇔ x ≤ 5, x ∈ ( - 00, 5], deci
x ∈ N si x ∈( - 00, 5} ⇒ x ∈{ 0,1,2,3,4,5}, deci multimea A este
A = { 0,1,2,3,4,5}
pt. multimea B, inecuatia 3x + 1< 15⇔3x < 15 - 1⇔ 3x < 14⇒ x< 14/3⇒
x ∈ ( - 00, 14/3) si x ∈ N ⇒ x ∈ { 0,1,2,3,4}, doar nr/ naturale 14:3 =4,6⇒ deci se iau nr. pana la 4
B={0,1,2,3,4,5} si A =0,1,2,3,4,5,}⇒ A = B ={0,1,2,3,4,5}
A U B= {0,1,2,3,4,5}, A inters. B = {Ф}, A- B ={Ф}, B - A ={Ф"