# Homework Help: Did i do this right? l 4-2x l > 8

1. Mar 9, 2013

### elmosworld403

l 4-2x l >8

4-2x>0 4-2x>8
-2x>-4 -2x>4
x>2 x>-2

4-2x<0 4-2x<8
-2x<-4 -2x<4
X<2 X<-2

-2< X < 2

Do I have to keep doing the 4-2x>0 4-2x<0 Even tho it doesn't say it in the question?
It is also asking me to graph it, just graph it on a number line?

Last edited: Mar 9, 2013
2. Mar 9, 2013

### jbunniii

You can see that the answer can't be (-2,2) by taking a number in that interval such as 0 and noticing that it doesn't satisfy the inequality.

I'm not sure why you wrote 4 - 2x > 0 and 4 - 2x < 0. These are mutually exclusive (they can't both be true), and in any case neither one of them follows from the original inequality.

|4-2x| > 8 means precisely that 4-2x > 8 or 4-2x < -8.

3. Mar 9, 2013

### elmosworld403

Kk so i don't have to do the zeros. I redid the question.

-(4-2x)>8
-4+2X>8
2x>12
X>6

4-2x>8
-2x>4
x>-2

Interval notation

(-2,∞)

4. Mar 9, 2013

### jbunniii

OK
No, when you divide by sides by -2 you have to reverse the inequality, so the last line should be x < -2.

5. Mar 9, 2013

### pierce15

Are you sure that this should be in the calculus section?