- #1
amp92
- 2
- 0
I'm having a problem with providing counter examples when disproving a statement. For example A - (B U C) = (A - B) U (A - C). The solution given was A = {a}, B = {a} and C = empty set.
My question is how can you work this out - i was told it's possible from the Venn diagrams but I'm not sure how this works. My method to find counter examples is usually to make A = {a}, B = {b} and C = {c} and then show the LHS doesn't equal the RIGHT. If it does i make changes to either A,B,C (i.e. use empty sets etc.). So for the example above can't you have A = {a}, B = {a} and C = {c}. How do you know C is an empty set?
Is it ok to stick with my method or can someone explain how to use the Venn diagrams for the LHS and RHS to find the counter examples.
Thank you :)
My question is how can you work this out - i was told it's possible from the Venn diagrams but I'm not sure how this works. My method to find counter examples is usually to make A = {a}, B = {b} and C = {c} and then show the LHS doesn't equal the RIGHT. If it does i make changes to either A,B,C (i.e. use empty sets etc.). So for the example above can't you have A = {a}, B = {a} and C = {c}. How do you know C is an empty set?
Is it ok to stick with my method or can someone explain how to use the Venn diagrams for the LHS and RHS to find the counter examples.
Thank you :)