Is |x| = y-z?

[Guest]

Is |x| = y-z?

1) x+y = z

2) x<0

Can you please explain how to approach this question? I answered it correctly but I don't think I fully understand how I came up with the answer.

Thank you!

[ayang]

Is |x| = y-z?

1) x+y = z

2) x<0


Statement 2 alone: The first thing to do is take the easy statement, Statement 2, which is clearly not sufficient by itself. Eliminate B and D.

Statement 1 alone:

Statement 1 should be manipulated to find x:

x + y = z
x = z - y

If x = z - y, is |x| = y-z?

Note that y - z = - (z - y). So the question asks, is |x| = - x?

From statement 1 alone, you don't know if this is the case, so eliminate answer choice A.

Statements 1 and 2 together:

From statement 2, you know that x is negative. So - x will equal |x|.
From statement 1, you know that x = z - y

Therefore:
- x = y -z
|x| = y-z

Answer choice C.

Hope that this is helpful! - Andrew





Can you please explain how to approach this question? I answered it correctly but I don't think I fully understand how I came up with the answer.

Thank you!

[Guest]

Thank you, Andrew! This is very helpful!

Jenna

[abdul_tt]

Ron,
Could you please tell me how you'd approach this question. I'm satisfied with the above answer, but wondering if there is another approach to this question.

[RonPurewal]

Ron,
Could you please tell me how you'd approach this question. I'm satisfied with the above answer, but wondering if there is another approach to this question.

here's another thread:
is-x-y-z-t8626.html

you can also plug in numbers.

statement (2): obviously insufficient, as there is no information at all about y or z

statement (1):
x, y, z = 1, 2, 3 --> gives "no" the question
x, y, z = 0, 0, 0 --> gives "yes" to the question
so, insufficient

together:
go ahead and plug in as many sets of x, y, z as you want (as long as they satisfy both conditions); you will notice that you get "yes" every time. just keep plugging until you are convinced.

so, (c)