# please check my work: simplify 28.43 + (-13.17) + |2.07|

#### belle&lt;3

##### New member
Evaluate the sum 28.43 + (-13.17) + |2.07|.

28.43 + (-13.17) + |2.07|
28.43 -13.17 + |2.07|
15.6 + |2.07|
= 17.33

I'm "iffy" on absolute value. Are there any rules I should know?

#### Subhotosh Khan

##### Super Moderator
Staff member
Re: Just wanted to know if my math was correct.

belle<3 said:
Evaluate the sum 28.43 + (-13.17) + |2.07|.

28.43 + (-13.17) + |2.07|
28.43 -13.17 + |2.07|

= 15.26 + 2.07

= 17.33

I'm "iffy" on absolute value. Are there any rules I should know?

For this problem - treat the absolute value as if it were a positive number added.

#### Denis

##### Senior Member
Re: Just wanted to know if my math was correct.

belle<3 said:
28.43 -13.17 + |2.07|
15.6 + |2.07|
C'mon Bella: is 28.43 - 13.17 = 15.6 ?

AND: | n | and |-n | are both simply n : it's that simple :idea:

#### Loren

##### Senior Member

"AND: | n | and |-n | are both simply n : it's that simple" is not always true.

What if n = -3.
Plugging that into your statement gives us...

| -3 | and |-(-3) | are both simply -3. That is not true.

#### Denis

##### Senior Member
Well Loren, I'm "trying (not too successfully, I guess" to say that,
IN ALL CASES, || means a positive; or if you remove the "||",
change a negative value to positive.

#### skeeter

##### Senior Member
definition of absolute value ...

|x| = x if x > 0

|x| = -x if x < 0

#### stapel

##### Super Moderator
Staff member
skeeter said:
definition of absolute value ...
|x| = x if x > 0
|x| = -x if x < 0
Denis said:
May I state, Sir, that "the absolute value of (-8)" = |-8| = 8
The two say the same thing!

In the first quote above, the "minus" (as the site in the link explains) means "change the sign". So, applying the definition from the first reply to the example in the second reply, we get:

. . . . .Find the absolute value of x for x = -8.

. . . . .absolute value of x = -8: | x | = | -8 | = 8 = -(-8) = -x

See? :wink:

Eliz.

#### belle&lt;3

##### New member
oh soooorry for the typo! I knew it was 15.26 that's how I got 17.6! :lol:

Thank you for the definition of absolute value that helps.