Q. show there exist irrational numbers x,y for which xy is rational
Consider 2: Let's consider the irrational number 2. We know that 2 is irrational.
Consider (2)(2): Now let's consider another irrational number, which is (2)(2). It's not immediately clear whether this number is rational or irrational.
Check rationality: If (2)(2) is rational, then we have found our x and y: x=2 and y=2, and xy=(2)(2) is rational.
Set x and y: If (2)(2) is irrational, then let's set x=(2)(2) and y=2. Now we will calculate xy.
Calculate xy: Calculating xy gives us ((2)(2))(2)=(2)(2⋅2)=(2)2.
Simplify result: Simplifying (2)2 gives us 2, which is a rational number.
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