Lesson: The Something Method

Comment on The Something Method

outbox thinking :d
gmat-admin's picture

Thanks!

How would one know if this technique should be used and will yield an answer ?
gmat-admin's picture

You can use it in situations where an algebraic expression is grouped together.

Two rudimentary examples:

(2)(x² - x - 9) = 6
This tells us that (x² - x - 9) = 3

12/(x² - x - 9) = 3
This tells us that (x² - x - 9) = 4

This is a good method but any other method to solve this?
gmat-admin's picture

We can just apply basic equation-solving techniques.

Given: (12y)/(5y + 1/x) = 2

Multiply both sides by (5y + 1/x) to get: (12y) = 2(5y + 1/x)

Expand: 12y = 10y + 2/x

Subtract 10y from both sides: 2y = 2/x

Multiply both sides by x to get: 2xy = 2

Divide both sides by 2 to get: xy = 1

Voila!

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