# Math Help - modulus

1. ## modulus

-abs(x+1)+abs(1-x)=2 can anyone tell me how to solve this with a sound approach i dont have any clue what to start with
abs is mod(modulus)
answer is x is less than or equal to -1

2. ## Re: modulus

Originally Posted by abdulrehmanshah
[INDENT]-abs(x+1)+abs(1-x)=2 can anyone tell me how to solve this with a sound approach i don't have any clue what to start with
answer is x is less than or equal to -1
First $|1-x|=|x-1|$ so the problem is $|x-1|-|x+1|=2$.

We have three regions: $(-\infty,-1],~(-1,1],~\&~[1,\infty)$.

Is it true for $x=3~?$ NO! So the third region is out.

Is it true for $x=0~?$ NO! So the second region is out.

Is it true for $x=-5~?$ So?

ok

4. ## Re: modulus

But, of course, if the right-hand side is 1 instead of 2:
$$|x-1|-|x+1|=1$$
then the equation cannot be solved by picking one value from each of the three regions.