Hint for Section 3.5 Question 3

3. When you are given a proposition such as  x · y = x· yand asked to determine if it is true or false, it is usually a good idea to try substituting some values for the variables x and y. If after trying several different values, it always seems to be true, you might get a clue as to why it is true and then you can use the clue to write a proof. If you find some values which make the proposition false, then you have your counter-example.

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