Absolute Value: Consider Two CasesDate: 08/21/97 at 13:27:59 From: Mandy Pedro Subject: Algebra 2 I am having problems with this one section in my Algebra 2 course. It is about absolute value and they tell you to solve the equation. Here is a example: |7+3a| = 11-a . Thank you a lot. Date: 08/27/97 at 12:03:24 From: Doctor Rob Subject: Re: Algebra 2 To solve equations like |7 + 3*a| = 11 - a, you have to consider two cases. Recall |x| = x if x >= 0, and |x| = -x if x < 0. Case 1: 7 + 3*a >= 0, which can be rewritten as a >= -7/3. Then you are solving 7 + 3*a = 11 - a, which yields a = 1. Remember to check that your answer still satisfies the condition a >= -7/3 (it does). Case 2: 7 + 3*a < 0, which can be rewritten as a < -7/3. Then you are solving -(7 + 3*a) = 11 - a, which yields a = -9. Again, we must remember to check that -9 < -7/3 (it is). Thus there are two answers: a = 1 and a = -9. Most problems of this type are handled in a similar way. -Doctor Rob, The Math Forum Check out our web site! http://mathforum.org/dr.math/ |
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