Q. Is ab = 1 ?
(1) aba = a
(2) bab = b
OA is E. Can someone explain?
Regards
MSD
Gmat Plus 2
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- ronniecoleman
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IMO E is correct
1. a = 0 ab = 1
2. b = 0 , ab = 1
now both 1 & 2
ab = 1
or
a = 0 , b = 0
1. a = 0 ab = 1
2. b = 0 , ab = 1
now both 1 & 2
ab = 1
or
a = 0 , b = 0
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Ronnieronniecoleman wrote:IMO E is correct
1. a = 0 ab = 1
2. b = 0 , ab = 1
now both 1 & 2
ab = 1
or
a = 0 , b = 0
I still don't understand how your supposition that when a = 0, ab = 1 is possible.
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A)a^2b=a
b=a/a^2
b=a but cannot say if ab=1
B)same line a=b
together as well not sufficient
I think one has to remember even if u think this could be easily answered ( which i did intially ...but then i thought this cant be easy! some catch )
so eventually got the OA
OA E
b=a/a^2
b=a but cannot say if ab=1
B)same line a=b
together as well not sufficient
I think one has to remember even if u think this could be easily answered ( which i did intially ...but then i thought this cant be easy! some catch )
so eventually got the OA
OA E
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Thanks for explaining the logic..mental wrote:I) aba = a
aba - a =0
a(ab -1) = 0
a = 0, or ab = 1
II) bab = b
like I....... b=0 or ab=1
only one root common in both statements, ab=1
Ans should be C ?
I agree with you regarding the OA.
using both equations we have a common solution so OA should be C
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I divided by 'a' in (1) and 'b' in statement (2) and got D. Then I realized that when you divide by a variable you potentially eliminate a solution (i.e. the variable could =0) which could be critical to a DS answer.
My thoughts on the responses above:
a=0 and b=0 aren't mutually exclusive! So a=0 and b=0 are possible common anwers.
There's two possibilities, that a=0 AND b=0 or that ab=1 that make both statements true i.e. ab could equal 1 or could equal 0. So C cannot be the correct answer.
IMO E
My thoughts on the responses above:
a=0 and b=0 aren't mutually exclusive! So a=0 and b=0 are possible common anwers.
There's two possibilities, that a=0 AND b=0 or that ab=1 that make both statements true i.e. ab could equal 1 or could equal 0. So C cannot be the correct answer.
IMO E
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Could any of the math specialists please explain how to approach such a question?
stm1
aba = a
a(ab -1) = 0
a = 0, or ab = 1
stm2
Similar to stm1, b = 0, or ab = 1
Why cannot we derive ab=1 from both these statements and say answer is C?
stm1
aba = a
a(ab -1) = 0
a = 0, or ab = 1
stm2
Similar to stm1, b = 0, or ab = 1
Why cannot we derive ab=1 from both these statements and say answer is C?
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Good question! I am not sure if this helps any but let me try.Why cannot we derive ab=1 from both these statements and say answer is C?
Pick a=0 b=0 for stmt I and II. It is true
a=1 b=1 is also true. No where its mentioned that a and b are distinct so our consideration a=0 b=0 ; a=1 b=1 holds good.
ab=1 is true (redundant info from both statements since from either of the statements we can get this info)
I am sure others may be able to explain better also!
- logitech
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This is a YES / NO question.msd_2008 wrote:Q. Is ab = 1 ?
(1) aba = a
(2) bab = b
OA is E. Can someone explain?
Regards
MSD
Is ab=1 ? YES IT IS - Sufficient , NO IT IS NOT = sufficient MAYBE = INSUF
St1 and St2 both have two solutions
St1+St2
a=0 & b =0
or AB=1 a=1/b
well...
ab can be 0 or ab=1
We are not sure...so MAYBE means E in yes/no DS question
Choose E
LGTCH
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Logitech, if the question was similar to:logitech wrote:This is a YES / NO question.msd_2008 wrote:Q. Is ab = 1 ?
(1) aba = a
(2) bab = b
OA is E. Can someone explain?
Regards
MSD
Is ab=1 ? YES IT IS - Sufficient , NO IT IS NOT = sufficient MAYBE = INSUF
St1 and St2 both have two solutions
St1+St2
a=0 & b =0
or AB=1 a=1/b
well...
ab can be 0 or ab=1
We are not sure...so MAYBE means E in yes/no DS question
Choose E
What is x: stm1: (x-1)(x-2)=0; stm2: (x-1)(x-3)=0
What would you choose?
- logitech
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In this case I would choose Cmuzali wrote:
Logitech, if the question was similar to:
What is x: stm1: (x-1)(x-2)=0; stm2: (x-1)(x-3)=0
What would you choose?
Because it is not a YES or NO question and x=1 satisfies both equation. Am I right ?
LGTCH
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"DON'T LET ANYONE STEAL YOUR DREAM!"