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Mathematics 22 Online
OpenStudy (anonymous):

If the difference of two numbers is less than the sum of the numbers, which of the following must be true?

OpenStudy (anonymous):

Ok, what are the choices?

OpenStudy (anonymous):

A. Neither number is positive

OpenStudy (anonymous):

B. At least one of the numbers is positive

OpenStudy (anonymous):

C. Exactly one of the numbers is positive

OpenStudy (anonymous):

D. Both numbers are positive

OpenStudy (anonymous):

E. None of these statements must be ture

OpenStudy (anonymous):

true

OpenStudy (anonymous):

those are my choices

OpenStudy (anonymous):

so

OpenStudy (anonymous):

D.

OpenStudy (anonymous):

(x-y)<(x+y)

OpenStudy (anonymous):

Nope

OpenStudy (anonymous):

Answer booklet says B.

OpenStudy (anonymous):

At least one of the numbers is positive

OpenStudy (anonymous):

so

OpenStudy (anonymous):

2+2 and 2-2?

OpenStudy (anonymous):

ehh?

OpenStudy (anonymous):

so they are saying the difference is 4 and the sum is 0?

OpenStudy (anonymous):

wah

OpenStudy (anonymous):

anything, guys?

OpenStudy (anonymous):

you guys still there?

OpenStudy (anonymous):

ehh

OpenStudy (chihiroasleaf):

how about like this..., let x,y be the numbers, such that x>y,so x-y < x+y -y<y 2y>0 y>0 I assume that x>y, then x>0, I'm not sure about this..,

OpenStudy (anonymous):

x is greater than 0

OpenStudy (anonymous):

x is greater than y...

OpenStudy (anonymous):

then, should not both the numbers be positive?

OpenStudy (anonymous):

Yes, the answer is B

OpenStudy (anonymous):

how?

OpenStudy (anonymous):

Only one number needs to be positive.

OpenStudy (anonymous):

chihi said both the numbers are positive

OpenStudy (anonymous):

how?

OpenStudy (anonymous):

y is greater than 0

OpenStudy (anonymous):

x is greater than y

OpenStudy (anonymous):

so they should both be positive

OpenStudy (anonymous):

The first # can be negative. Then, if you subtract a positive #, that answer is smaller than if you were to add a positive #.

OpenStudy (anonymous):

hold up

OpenStudy (anonymous):

So, the answer is B.

OpenStudy (anonymous):

-2-2=-4

OpenStudy (anonymous):

-2+2=0

OpenStudy (anonymous):

ahh

OpenStudy (anonymous):

so not

OpenStudy (anonymous):

2+2=4?

OpenStudy (anonymous):

2-2=0?

OpenStudy (anonymous):

And 0 is greater than -4, so the answer is B.

OpenStudy (chihiroasleaf):

when we talk about the difference, isn't it the absolute value? so the difference between x and y, it's |x-y|, that's why I assume x>y, how?

OpenStudy (anonymous):

k

OpenStudy (anonymous):

so

OpenStudy (anonymous):

ehh

OpenStudy (anonymous):

(x+y)<(x-y)

OpenStudy (anonymous):

x+y<x-y

OpenStudy (anonymous):

2y<0

OpenStudy (anonymous):

y<0

OpenStudy (anonymous):

x+0<x-0

OpenStudy (chihiroasleaf):

I got confuse let's ask others @sauravshakya @hartnn

OpenStudy (anonymous):

so y<0

OpenStudy (anonymous):

It's actually a poorly-worded problem, because if one interprets the question for EVERY set of x and y (that is, if you allow x and y to be switched around), THEN they have to be both positive.

OpenStudy (anonymous):

yeah

OpenStudy (anonymous):

x-y<x+y

OpenStudy (anonymous):

and this is a PSAT QUESTION!

OpenStudy (anonymous):

so

OpenStudy (anonymous):

x equals 0

OpenStudy (anonymous):

But IF (and this is the way they mean the problem to be) they allow the x and y to picked so that the first # is negative, THEN only one number needs to be positive. It's a very VERY poorly worded question.

OpenStudy (anonymous):

which is neither positive or negative?

OpenStudy (anonymous):

so

OpenStudy (anonymous):

y<0

OpenStudy (anonymous):

so lets say

OpenStudy (anonymous):

x+1<x-1

OpenStudy (anonymous):

x<x-2

OpenStudy (anonymous):

0<2?

OpenStudy (anonymous):

0<-2?

OpenStudy (anonymous):

so, I understand y<0

OpenStudy (anonymous):

but how do we solve for x?

OpenStudy (anonymous):

luisz, it would be helpful if you did not break up your posts into so many little posts. It is quite impossible to follow your train of thought when you do that.

OpenStudy (anonymous):

x cancels to be 0 in the problem

OpenStudy (anonymous):

sorry

OpenStudy (anonymous):

I'll let you guys talk now

OpenStudy (chihiroasleaf):

if we talk about the difference, I think it doesn't matter which number at first, the difference between -1 and 2 is 3.., no matter which number at the front.., right?

OpenStudy (anonymous):

I already gave my answer. Just read it.

OpenStudy (anonymous):

The first # can be negative. Then, if you subtract a positive #, that answer is smaller than if you were to add a positive #.

OpenStudy (anonymous):

-2-1=-3

OpenStudy (anonymous):

-2+1=-1

OpenStudy (anonymous):

difference is smaller

OpenStudy (anonymous):

As I said earlier also, I think Both numbers must be positive.

OpenStudy (anonymous):

but only one number needs to be positive

OpenStudy (anonymous):

like tcarrol said, this a poorly worded problem

OpenStudy (anonymous):

But why would they poorly word a PSAT QUESTION?

OpenStudy (anonymous):

The first # can be negative. Then, if you subtract a positive #, that answer is smaller than if you were to add a positive #. It's actually a poorly-worded problem, because if one interprets the question for EVERY set of x and y (that is, if you allow x and y to be switched around), THEN they have to be both positive. But IF (and this is the way they mean the problem to be) they allow the x and y to picked so that the first # is negative, THEN only one number needs to be positive. It's a very VERY poorly worded question.

hartnn (hartnn):

(x-y)<x+y 2y>0 y>0 so y must be positive. now for x, let x be positive, ex 4-2<4+2<----correct! let x be negative. -4-4<-4+2<-----correct! so x can be + or - so B. atleast.

hartnn (hartnn):

-4-2<-4+2<-----correct!

OpenStudy (anonymous):

ahh

OpenStudy (anonymous):

must is the key word...

OpenStudy (anonymous):

but x could be positive

OpenStudy (anonymous):

whatever

OpenStudy (anonymous):

lets end this discussion

OpenStudy (anonymous):

I am going to make lunch now

OpenStudy (anonymous):

see you guys end a bit

hartnn (hartnn):

yup, x could be + or - any, so atleast 1 should be +.

hartnn (hartnn):

see ya :)

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