If (x-5)(y+2) = 0 which of the following must be true?

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If (x-5)(y+2) = 0 which of the following must be true? [#permalink]

31 Jan 2013, 07:41

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If (x-5)(y+2) = 0 which of the following must be true?

(A) x = y
(B) x > y
(C) x < y
(D) xy = -10
(E) None of the above

[Reveal] Spoiler: OA

Last edited by Bunuel on 31 Jan 2013, 07:50, edited 1 time in total.

Renamed the topic and edited the question.

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Re: Please help me to solve this question [#permalink]

31 Jan 2013, 07:55

sananoor wrote:

if (x-5)(y+2)=0 which of the following must be true?

(A)X=Y
(b) X>Y
(C)X<Y
(d)XY=-10
e.none of th above

If (x-5)(y+2) = 0 which of the following must be true?

(A) x = y
(B) x > y
(C) x < y
(D) xy = -10
(E) None of the above

From (x-5)(y+2) = 0 it follows that either x=5 or y=-2.

(A) x = y --> not necessarily true. Consider x=5 and y=0.
(B) x > y --> not necessarily true. Consider x=5 and y=10.
(C) x < y --> not necessarily true. Consider x=5 and y=0.
(D) xy = -10 --> not necessarily true. Consider x=5 and y=0.

Thus, none of the statements must be true.

Answer: E.

Hope it's clear.

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Re: If (x-5)(y+2) = 0 which of the following must be true? [#permalink]

31 Jan 2013, 09:10

i didnt get this how u consider X and Y values when it is given in the question
If (x-5)(y+2) this means that X = 5 and Y = -2
thus XY = -10 and X > Y..

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Re: If (x-5)(y+2) = 0 which of the following must be true? [#permalink]

31 Jan 2013, 09:20

sananoor wrote:

i didnt get this how u consider X and Y values when it is given in the question
If (x-5)(y+2) this means that X = 5 and Y = -2
thus XY = -10 and X > Y..

(x-5)(y+2) = 0 means that EITHER x=5 OR y=-2. For example, if x=5, then y can be any number. The same way, if y=-2, then x can be any number.
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Re: If (x-5)(y+2) = 0 which of the following must be true? [#permalink]

31 Jan 2013, 17:08

Bunuel wrote:

sananoor wrote:

i didnt get this how u consider X and Y values when it is given in the question
If (x-5)(y+2) this means that X = 5 and Y = -2
thus XY = -10 and X > Y..

(x-5)(y+2) = 0 means that EITHER x=5 OR y=-2. For example, if x=5, then y can be any number. The same way, if y=-2, then x can be any number.

Bunuel, although your solution is perfect, I would just point out a rewording suggestion on your last comment. (x-5)(y+2) =0 means that x = 5 OR y =-2 (without the EITHER). Obviously both equalities COULD happen simultaneously, but they don't HAVE TO happen simultaneously in order for the equation in stem to be valid
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Re: If (x-5)(y+2) = 0 which of the following must be true? [#permalink] 31 Jan 2013, 17:08

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If (x-5)(y+2) = 0 which of the following must be true?

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