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24 Sep 2016, 07:01
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I know that the usual rule is that we should have n equations to solve for n unknowns, except when the equations are equivalent, for example x+y=1 and 2x+2y=2. I have fallen for that trap before...
My question is, is that the only situation when having the same number of equations and unknowns will not work? Because as I go through my review, I find that I have been wasting time on data sufficiency questions checking if the equations will result in a solution.
In other words, as long as I have n unknowns and n equations that are NOT equivalent, can I always assume that they are sufficient?
My question is, is that the only situation when having the same number of equations and unknowns will not work? Because as I go through my review, I find that I have been wasting time on data sufficiency questions checking if the equations will result in a solution.
In other words, as long as I have n unknowns and n equations that are NOT equivalent, can I always assume that they are sufficient?
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.
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24 Sep 2016, 07:24
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Hi,
There are three ways how DS can trick you:
1.) Your example. Statement 1 is the same statement (multiplied by two) as Statement 2.
2.) It could ask you for the solution for an equation, while the systems of equations will give you two. You will get a quadratic equation in this case
3.) Sometimes you don't need n equations for n variables.
Imagine the equation: a+b+c=a+3. The variable A is not needed.
Summary:
1.) Same equation -> You still need n equations for n variables
2.) You have n variables, but you get two answers -> Not sufficient
3.) Not needed variables are introduced to confuse you
Best,
DB
There are three ways how DS can trick you:
1.) Your example. Statement 1 is the same statement (multiplied by two) as Statement 2.
2.) It could ask you for the solution for an equation, while the systems of equations will give you two. You will get a quadratic equation in this case
3.) Sometimes you don't need n equations for n variables.
Imagine the equation: a+b+c=a+3. The variable A is not needed.
Summary:
1.) Same equation -> You still need n equations for n variables
2.) You have n variables, but you get two answers -> Not sufficient
3.) Not needed variables are introduced to confuse you
Best,
DB
24 Sep 2016, 20:48
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Bookmarks
Thanks, DB, useful stuff to keep in mind
DarkBlizzard
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 Quantitative Questions 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!
