Mathematics joy
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1 Mar 2009, 22:32
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Journals
ok guys i have todays math problem for you
|2x-1|-|x+5|=3
solve for x
(keep in mind that you get no points if you dont show how you got to the answer)
Edit: Come on guys nobody has solved it yet :) exept me! I hold here the solution to this problem. Whoever gets the right answer first (with your means to get there written out) will score 3 points and will be the first on the crossfire math ranking.
Edit2 : Loctarar has written the method to solve it but he is reluctant to write out the whole solution, therefore people still have a chance to get 3 points. ;)
Edit3: we have a winner: rize http://www.crossfire.nu/?x=user&mode=view&id=9412 wrote the right solution, http://www.pic-upload.de/view-1604318/1.jpg.html he is now a proud leader of the crossfire math rank http://www.crossfire.nu/?x=user&mode=view&id=15652
|2x-1|-|x+5|=3
solve for x
(keep in mind that you get no points if you dont show how you got to the answer)
Edit: Come on guys nobody has solved it yet :) exept me! I hold here the solution to this problem. Whoever gets the right answer first (with your means to get there written out) will score 3 points and will be the first on the crossfire math ranking.
Edit2 : Loctarar has written the method to solve it but he is reluctant to write out the whole solution, therefore people still have a chance to get 3 points. ;)
Edit3: we have a winner: rize http://www.crossfire.nu/?x=user&mode=view&id=9412 wrote the right solution, http://www.pic-upload.de/view-1604318/1.jpg.html he is now a proud leader of the crossfire math rank http://www.crossfire.nu/?x=user&mode=view&id=15652
(-2x+1)-(-x-5)-3=0
-2x+1+x+5-3=0
-x-3=0
x = -3
and the other one is 9..
(2x-1)-(x+5)=3
2x-1-x-5=3
x=1+3+5
x=9
x<-5..........
-(2x-1)-(-(x+5))=3
-2x+1+x+5=3
-x+6=3
x=-3
-5<x<1 ..........
(2x-1)-(-(x+5)=3
2x-1+x+5=3
3x=-1
x= -1/3
i donno if it is right but it must be smth laik this!
1. x<=-5
2. x>-5 and x <= 1/2
3. x > 1/2
See if the equation has solution after you expand the modules in each case.
Reasons: A module |x-a| can be either x-a if x > a or a - x if x <= a. So if x <= -5 you have: (1-2x) - (-5 - x) = 3 etc.
x-6=3
x=3+6
x=9
1. If x < -5 => x = 3 is solution, but outside the interval so it's not good
2. If x >-5 and x < 1/2 => x = -7/3 which is between -3 and -2 so it's a good solution
3. If x > 1/2 => x = 9 (a good soluition).
(ok, seems like i was really too slow)
\:D/
2x-1-x+5-3=0
2x-x = x
-1+5-3=1
x+1=0
-> x=-1
-(2x-1)-(-(x+5) = 3
-1 * 2x - 1 = -2x +1
-1 * x + 5 = -x -5
(-2x+1)-(-x-5)-3=0
-2x -x = -3x
+1-5-3=-7
x = -7/3 (like locatoraraoaoro said)
FAILED