Need Algebra help - quick!

[Barb D]

DS has a test on this tomorrow, and neither of us has a clue what this means.

Here's the problem:
Write an open sentence involving absolute value for "The price was within $10 of his $100 limit."

So far we understand that $90 <= p <= $100. But where does absolute value fit in? Maybe if I'd had more than a few hours of sleep last night and he hadn't been out sick last week this would be obvious to us!

Edit: When it says "within" should I assume that it has to be under $100, or could it be over?

 

[Barb D]

Originally posted by Barb D
DS has a test on this tomorrow, and neither of us has a clue what this means.

Here's the problem:
Write an open sentence involving absolute value for "The price was within $10 of his $100 limit."

So far we understand that $90 <= p <= $100. But where does absolute value fit in? Maybe if I'd had more than a few hours of sleep last night and he hadn't been out sick last week this would be obvious to us!

Edit: When it says "within" should I assume that it has to be under $100, or could it be over?

|$100-price| <= $10 ??? Does this make sense? I'm talking to myself here...

If the price was $91, | $100-$91 | <= $10.
If the price was $109, | $100 - $109 | <= $10.

I think this may be it. Do I have it?

 

[ILMOUSE]

I like your answer and it makes sense. It has been too many years since Algebra but I think you are right. Hope someone who teaches math responds.

 

[FroggyinArk]

that looks good barb,, not sure of the exacts anymore, but i think you've grasped the idea.

 

[Gupsdad]

Since the difference of the price and 100 must be less than or equal to $10, then there are two possible results:

| price - 100| <= 10

or

| 100 - price| <= 10

It does not matter which order you use inside the absolute value. The value will be positive.

Very nice work Barb - not bad for not doing Algebra for a while.

Tom (Jessica's DH)

 

[Barb D]

Thanks, everyone! He's doing the rest of the problems that way and he'll confirm it with his teacher before the test.

I've been able to handle all his algebra up until this. I don't recall seeing this when I took Algebra in, uh, 1975.