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Learning Multiple Methods
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When you sit for the GMAT, you'll want to have a quick reaction to every question. See the question, recognize what needs to be done, and do it. No mulling over your options or changing gears halfway through to start a new approach.
This kind of confidence must be learned in your study time. The mistake many students make is to learn several methods for every question and trust that the best approach will magically be deployed during the GMAT itself.
Multiple Strategies for Multiple Scenarios
Many GMAT questions can be solved using multiple methods. In some cases, it's valuable to learn more than one approach--if and only if you take the time to determine which one is more effective, and what makes one approach better than another.
A perfect example (and one that isn't too complicated) is systems of equations. There are two common ways to solve them: "combination" and "substitution." If you see two equations like this:
2x + 7y = 41
2x - y = 1
...either method would work, but the scenario is tailor-made for combination. Subtract one equation from another, and the result is 8y = 40, which can easily be solved. Combination worked because two of the coefficients were the same. It will always be effective in that kind of situation.
By constrast, consider another system:
2x + 7y = 41
3x + 5y = 34
In this case, we don't have any similar coefficients, not even anything that could easily be multiplied to generate similar coefficients. This is a clear case for substitution.
Again: Either of these systems could be solved by combination or substitution, but in each case, one of the methods is far superior to the other. Understanding why is the key to having the correct approach at your fingertips on test day.
Applying Multiple Methods
Let's say you familiarize yourself with three approaches to the same problem. In learning the three, I hope that you can figure out for yourself which one works best for that specific problem--one of them either involved the least calculation, or was fastest, or was in some way superior to the others.
That doesn't mean those other approaches are worthless. They are probably applicable to some other problems, and your next task is to figure out how. Are there any details in the problem that make it particularly susceptible to one approach? What would you do if those details weren't there? Have you seen another question on a similar topic? If so, which of the strategies would work the best on that problem?
The key point here is that strategies are only useful insofar as they are the best approaches to specific problems. If you continually practice a problem solving method just to discover that it always takes five minutes, it probably isn't the best approach to any problem. Or if you learn a neat trick but you never see a GMAT problem it applies to, it probably won't be very valuable on test day.
Go ahead and learn more than one approach any time you think it might be useful. But before you study it hard or incorporate it into your overall strategy, make sure it has measurable value.
About the author: Jeff Sackmann has written many GMAT preparation books, including the popular Total GMAT Math, Total GMAT Verbal, and GMAT 111. He has also created explanations for problems in The Official Guide, as well as 1,800 practice GMAT math questions.
|Total GMAT Math
The comprehensive guide to the GMAT Quant section. It's "far and away the best study material
available," including over 300 realistic practice questions and more than 500 exercises!