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What is the value of xy? (1) y = x + 1 (2) y = x^2 + 1

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gouribhalerao
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What is the value of xy? (1) y = x + 1 (2) y = x^2 + 1 [#permalink] New post  Updated on: 02 Feb 2023, 02:32
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What is the value of xy?

(1) y = x + 1
(2) y = x^2 + 1
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Originally posted by gouribhalerao on 04 Jan 2010, 00:37.
Last edited by Bunuel on 02 Feb 2023, 02:32, edited 2 times in total.
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kp1811
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Re: What is the value of xy? (1) y = x + 1 (2) y = x^2 + 1 [#permalink] New post  04 Jan 2010, 07:18
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gouribhalerao wrote:
Hi,

I have a doubt in one data sufficiency question of mba.com test. Can anyone please explain? The question is as follows.

What is the value of xy?
1. y = x + 1
2. y = x^2 + 1


stmnt1 - y = x+1 will not help us to get value of xy as we do not know the value of x. hence insuff
stmnt2 - y = x^2 + 1 same as 1. hence insuff

taking together we get x+ 1 = x^2 + 1 . we get x^2 = x . here x can be both 1 or 0
so we will get 2 different values for xy and even together both are not sufficient.

will go with E
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gouribhalerao
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Re: What is the value of xy? (1) y = x + 1 (2) y = x^2 + 1 [#permalink] New post  04 Jan 2010, 07:40
That's right. Thanks.
While solving the exam, I thought that if I consider both statements together, then x^2 = x. Then dividing both sides by x, I can get x=1. But yes, when here x can either be 0 or 1 and that changes the answer.
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Re: What is the value of xy? (1) y = x + 1 (2) y = x^2 + 1 [#permalink] New post  05 Jan 2012, 19:49
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Question is- can you find the exact value of xy.

1.
y=x+1
there is no way to determine value of x or y.
x can be a fraction, positive/negative integer.

Insufficient.

2.
y=x^2+1
all we know that y is positive.
Insufficient.

1+2
x+1=x^2+1
x^2=x
x is 0 or 1
y is 1 or 2

xy=0 or 2.
Insufficient

Hence E
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shinbhu
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Re: What is the value of xy? (1) y = x + 1 (2) y = x^2 + 1 [#permalink] New post  06 Jan 2012, 17:57
1. y=x+1. multiply both sides by x -> xy=x(x+1). No info on x, insuff.
2. y=x^2+1. multiply both sides by x -> xy=x(x^2+1). No info on x, insuff.

Together, equating both statements -> x+1 = x^2+1 -> x = 0, 1
Substituting gives y = 1,2.

Two solutions for xy -> E.
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gskang
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Re: What is the value of xy? (1) y = x + 1 (2) y = x^2 + 1 [#permalink] New post  07 Jan 2012, 02:15
Statement 1 and 2 considered individually are clearly insufficient. When we combine these two, we get two solutions as below:

x^2-x=0
x(x-1)=0
x=0 OR x=1

X=0, Y=1, XY = 0
X = 1, Y=2, XY = 2

Thus we have two solutions here and answer is E
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Re: What is the value of xy? (1) y = x + 1 (2) y = x^2 + 1 [#permalink] New post  18 Sep 2016, 16:29
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Correct answer is E

(1) y = x+1

NOT SUFFICIENT - we're not able to gather what x and y equals

(2) y = x^2 +1

NOT SUFFICIENT - same as (1)

Together - (1) + (2) --> x+1 = x^2 + 1

NOT SUFFICIENT
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Re: What is the value of xy? (1) y = x + 1 (2) y = x^2 + 1 [#permalink] New post  02 Feb 2023, 02:10
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Re: What is the value of xy? (1) y = x + 1 (2) y = x^2 + 1 [#permalink]
02 Feb 2023, 02:10
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