Date: 07/10/2001 at 16:15:50 From: Erin Cushing Subject: Math logic This is my question: A man is x years old at the year x squared, and he was born in 1806. I am supposed to solve for x. I got the answer, 43, but I don't know how to explain it in terms of logic. When I asked my teacher, he said to use the Modus Ponens rule and I shouldn't have a problem, but I am. Please help me. Thank you.
Date: 07/10/2001 at 17:55:38 From: Doctor Jaffee Subject: Re: Math logic Hi Erin, The Modus Ponens rule says that if you know that a statement, P, is true and that if P is true, then the statement Q is true, you can conclude that Q is true. Your conclusion was that the man was 43 years old in 1849, so that must be the statement Q. Now, what is the mathematical relation between the year a person was born, the current year, and the the person's age? If you can express that statement as an equation in terms of x, you will have the statement P. Give it a try and if you want to check your solution with me, write back. If you are having difficulties, let me know and show me what you have done so far, and I'll try to help you some more. Good luck. - Doctor Jaffee, The Math Forum http://mathforum.org/dr.math/
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