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IrinaOK
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DS_how many roots 21 Sep 2007, 11:27
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Hi there,
This topic has been closed and archived due to inactivity or violation of community quality standards. No more replies are possible here.
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b14kumar
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DS_how many roots 21 Sep 2007, 12:35
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IrinaOK
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Degree of an equation determines the number of roots of the equation.

Linear Equation has one root.

Since the equation given in the problem is linear and also ST1 clarifies that the value of A is not equal to 0 so, the equation will have only one root.

Hence A is SUFF.

- Brajesh
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IrinaOK
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DS_how many roots 21 Sep 2007, 12:53
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IrinaOK
DS

Degree of an equation determines the number of roots of the equation.

Linear Equation has one root.

Since the equation given in the problem is linear and also ST1 clarifies that the value of A is not equal to 0 so, the equation will have only one root.

Hence A is SUFF.

- Brajesh
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Why is B insuff?

-text in bold is not necessarily always true, consider x^2-4x+4=0, has only one root.
-A is not zero, does not mean A is not X

please explain, thank you.
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b14kumar
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DS_how many roots 21 Sep 2007, 13:19
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IrinaOK
b14kumar
IrinaOK
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Degree of an equation determines the number of roots of the equation.

Linear Equation has one root.

Since the equation given in the problem is linear and also ST1 clarifies that the value of A is not equal to 0 so, the equation will have only one root.

Hence A is SUFF.

- Brajesh


Why is B insuff?

-text in bold is not necessarily always true, consider x^2-4x+4=0, has only one root.
-A is not zero, does not mean A is not X

please explain, thank you.
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If A = 0 then A*x will be zero and there will not be any equation as such.
Furthermore, if you divide both sides of equations by A, then right hand side of equation will have B/A and if A is equal to Zero then B/A will become undefined.

B alone is insufficient because we have to know whether A is equal to zero or not. ST1 clarifies the same.

Since B is constant and does not violates the integrity of equation, we do not need the information whether B is equal to zero or not.
Even if B is equal to zero, equation will have only one root and value of the root will be -1.

And equation x^2-4x+4=0 has two roots but they are equal.

Hope it makes sense....

- Brajesh
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carpeD
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DS_how many roots 21 Sep 2007, 15:08
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b14kumar
IrinaOK
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Degree of an equation determines the number of roots of the equation.

Linear Equation has one root.

Since the equation given in the problem is linear and also ST1 clarifies that the value of A is not equal to 0 so, the equation will have only one root.

Hence A is SUFF.

- Brajesh
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i know i am kind of being the devil's advocate here but , what if A = x^2 or x^3 ?? How can we safely assume that A and B are constants.



Archived Topic
Hi there,
This topic has been closed and archived due to inactivity or violation of community quality standards. No more replies are possible here.
Where to now? Join ongoing discussions on thousands of quality questions in our Data Sufficiency (DS) Forum
Still interested in this question? Check out the "Best Topics" block above for a better discussion on this exact question, as well as several more related questions.
Thank you for understanding, and happy exploring!
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