- #1
Jamey
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Homework Statement
Suppose that a and b are real numbers. Prove that if [itex]a < b < 0[/itex], then [itex]a^{2} > b^{2}[/itex]
Homework Equations
Properties of inequalities?
The Attempt at a Solution
This is how I did the final proof:
Given that a and b are real numbers and [itex]a < b < 0[/itex], we notice that both a and b are negative since they are less than zero. It follows that, [itex]ab > b^{2}[/itex] and [itex]a^{2} > ab[/itex]. Because [itex]a^{2} > ab[/itex] and [itex]ab > b^{2}[/itex] it is evident that [itex]a^{2} > b^{2}[/itex]
Q.E.D.
Please let me know if my reasoning was, well, reasonable. If not, give me some suggestions for proof. This is a problem out of chapter 3 in Velleman's How To Prove It, Second Edition.