If (y+3)(y-1) (y-2)(y-1) = r(y-1), what is the value of y? : DS Archive
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If (y+3)(y-1) (y-2)(y-1) = r(y-1), what is the value of y?

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Manager
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If (y+3)(y-1) (y-2)(y-1) = r(y-1), what is the value of y? [#permalink]

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14 Jan 2008, 06:24
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If (y+3)(y-1) – (y-2)(y-1) = r(y-1), what is the value of y?

(1) r^2 = 25
(2) r = 5

not a difficlut one. a general query about DS. this was taken from Gmat Set 16.

OA in one of the following posts.
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14 Jan 2008, 06:36
GGUY wrote:
If (y+3)(y-1) – (y-2)(y-1) = r(y-1), what is the value of y?

(1) r^2 = 25
(2) r = 5

not a difficlut one. a general query about DS. this was taken from Gmat Set 16.

OA in one of the following posts.

You get 5(y-1) = r(y-1)

Now from (i) r= +/- 5

Thus y can be 0 or 1

So insufficient

From (ii)

As r=5, y=0

Thus sufficient.

"B" .
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14 Jan 2008, 06:53
LM wrote:

You get 5(y-1) = r(y-1)

Now from (i) r= +/- 5

Thus y can be 0 or 1

So insufficient

From (ii)

As r=5, y=0

Thus sufficient.

"B" .

Actually, if you'd continued one more step you'd have

5y-5=ry-1
y(5-r)=5-r

y=1

so, it seems that the answer lies in the Q itself.
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14 Jan 2008, 07:04
E

(y+3)(y-1) – (y-2)(y-1) = r(y-1)
5(y-1)=r(y-1)

r=5 satisfied both conditions.

5(y-1)=5(y-1) ==> y can be any number.
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Manager
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14 Jan 2008, 07:55
we can divide both sides by y-1 and get r=5.
So y can take any value other than 1, since we cat divide by zero,(y-1=0, when y=1)
Here y do not have a specific value. So what should be the answer.
i dont need S1 or S2
so is it ABCD or E??
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14 Jan 2008, 08:11
Simplifly the original expression and obtain (5-r)·(y-1)=0, that is r=5 or y=1

From S1 y can not be calculated
From S2 y can not be calculated
From S1 and S2 y can not be calculated

OA should be E.
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14 Jan 2008, 08:12
as I was solving this Q, I could not translate the math to any of the answers.

after looking at your posts, I guess that's how to do it:

we found that: r(y-1)=5(y-1).

(1) r=+/- 5

if r=-5 -> y=1
if r=5 -> y= any number ==> we need one value only. Insuff.

(2) r=5 -> y= any number ==> we need one value only. Insuff.

both statements do not give additional info.

E.
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15 Jan 2008, 23:46
GGUY wrote:
If (y+3)(y-1) – (y-2)(y-1) = r(y-1), what is the value of y?

(1) r^2 = 25
(2) r = 5

not a difficlut one. a general query about DS. this was taken from Gmat Set 16.

OA in one of the following posts.

I get E. divide both sides by y-1 --> left with y+3-y+2=r --> r=5... well 1 and 2 basically provide this info. No help at all.

Insuff.
Re: DS general Q   [#permalink] 15 Jan 2008, 23:46
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