can someone explain to me how -y=-|x|+2 turns into y=|x|-2

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- Jan 25th 2010, 06:01 PMwonderdquick easy question im sure
can someone explain to me how -y=-|x|+2 turns into y=|x|-2

- Jan 25th 2010, 06:02 PMSudharaka
Dear wonderd,

Multiply the whole equation by -1. - Jan 25th 2010, 06:46 PMwonderd
i dont understand, i do understand that to get the y by itself you divide by -1 but what are you suspose to do to the other side of the equal sign?

can someone explain how to divid -1 by -|x|+2 properly? - Jan 25th 2010, 07:12 PMfishcake
- Jan 25th 2010, 07:41 PMwonderd
thank you :)

- Jan 26th 2010, 03:43 AMHallsofIvy
Or, as sudharaka said,

**multiply**both sides of the equation by -1:

(-1)(-y)= (-1)(-|x|+ 2). The left is, of course, y and on the right you have (-1)(-|x|)+ (-1)(2)= |x|- 2. - Jan 26th 2010, 04:50 AMArchie Meade
Hi wonderd,

you may add y to both sides

$\displaystyle -y=-|x|+2$

$\displaystyle y-y=y-|x|+2$

$\displaystyle 0=y-|x|+2$

add |x| to both sides

$\displaystyle |x|=y+|x|-|x|+2$

$\displaystyle |x|=y+2$

subtract 2 from both sides

$\displaystyle |x|-2=y+2-2,\ |x|-2=y$

It's much quicker to multiply both sides by -1

or divide both sides by -1, but it helps to know how to juggle.