 Absolute Value Equations :
05-21-2008
I will do one of them only.
Take the absolute value equation |5x + 4| = 21
Remove the absolute value bars and make two cases:
5x + 4 = 21...This is case 1.
5x + 4 = -21...This is case 2.
Then check your answers.
Case 1:
5x + 4 = 21
5x = 21 - 4
5x = 17
x = 17/5
CHECK:
|5x + 4| = 21
|5(17/5) + 4| = 21
|17 + 4| = 21
|21| = 21
21 = 21...It checks!
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Case 2:
5x + 4 = -21
5x = -4 - 21
5x = -25
x = -25/5
x = -5
CHECK:
|5x + 4| = 21
|5(-5) + 4| = 21
|-25 + 4| = 21
|-21| = 21
21 = 21...It checks!
The solutions are -5 or 17/5.
mathman
Last edited by mathman; 07-23-2008 at 10:00 PM.
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