# Absolute Value Equations

• Sep 5th 2008, 12:54 PM
TNB
Absolute Value Equations
Need help w/ an absolute value problem where a no. is placed outside the equation within the absolute value signs-what should I do first?
• Sep 5th 2008, 01:10 PM
Jhevon
Quote:

Originally Posted by TNB
Need help w/ an absolute value problem where a no. is placed outside the equation within the absolute value signs-what should I do first?

since you chose to be vague, the most i can tell you is that

$|x| = \sqrt{x^2} = \left \{ \begin{array}{lr} x & \mbox{ if } x \ge 0 \\ & \\ -x & \mbox{ if } x < 0 \end{array} \right.$

so you need to split your equation in two to account for the possible change in sign of what's in absolute values.

example. $|3x - 1| = 2$

$\Rightarrow 3x - 1 = 2 \mbox{ or } -(3x - 1) = 2$

and continue
• Sep 5th 2008, 01:17 PM
TNB
It's like your final ex, save there's a number attached to the back end.

somthing like this...... 7 http://www.mathhelpforum.com/math-he...fe8dc286-1.gif

Sorry about the lack of detail. Just trying to speed things up.. Typing wise, anyhow.
• Sep 5th 2008, 01:20 PM
Jhevon
Quote:

Originally Posted by TNB
It's like your final ex, save there's a number attached to the back end.

somthing like this...... 7 http://www.mathhelpforum.com/math-he...fe8dc286-1.gif

Sorry about the lack of detail. Just trying to speed things up.. Typing wise, anyhow.

well, that's no problem. divide both sides by 7 first, you get

|3x - 1| = 2/7

then it is pretty much exactly like my example
• Sep 5th 2008, 01:23 PM
ILoveMaths07
Absolute value
In that case, do NOT multiply the 7 with the expression 3x - 1. That'll change the absolute value! Instead, divide 7 on both sides, and then proceed.

|3x - 1| = 2/7

Now proceed...

I hope that helps. :)

ILoveMaths07.

P.S. THIS IS MY FIRST POST!!! (Hi)
• Sep 5th 2008, 01:24 PM
Jhevon
Quote:

Originally Posted by ILoveMaths07
P.S. THIS IS MY FIRST POST!!! (Hi)

congrats! (Clapping)
• Sep 5th 2008, 01:39 PM
TNB
Thank you Jhevon.
Much thanks. Couldn't really remember whether to subtract or divide.....
• Sep 5th 2008, 01:45 PM
ILoveMaths07
You can't subtract because it's $7 * |3x - 1|$. You must divide the 7 on both sides.