Punjab Curriculum & Textbook Board
Class 8th : Math
Solution Guide
Operations On Sets
Exercise 1.2
Problem: 1(a)(i)
Verify:
A U B = B U A
and A ∩ B = B ∩ A, when
A = {1, 2,
3, …., 10}
B = {7, 8,
9, 10, 11, 12}
Solution:
A
= {1, 2, 3, …., 10}
B
= {7, 8, 9, 10, 11, 12}
A
U B = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10} U {7, 8, 9, 10, 11, 12}
Now
write collective values in both sets; called union set.
A
U B = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12}
B
U A = {7, 8, 9, 10, 11, 12} U {1, 2, 3, 4, 5, 6, 7, 8, 9, 10}
Now
write collective values in both sets; called union set.
B
U A = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12}
So, A U B = B U A
A
∩ B = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10} ∩ {7, 8, 9, 10, 11, 12}
Now
write common values in both sets; called common set.
A
∩ B = {7, 8, 9, 10}
B
∩ A = {7, 8, 9, 10, 11, 12} ∩ {1, 2, 3, 4, 5, 6, 7, 8, 9, 10}
Now
write common values in both sets; called common set.
B
∩ A = {7, 8, 9, 10}
So, A ∩ B = B ∩ A
