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y ≠ 0. What is the value of x/y?

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by Max@Math Revolution » Sun Apr 21, 2019 11:51 pm

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[GMAT math practice question]

y ≠ 0. What is the value of x/y?

1) x^2-6xy+9y^2=0
2) |x-3|+|y-1|=0
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Source: — Data Sufficiency |

by Max@Math Revolution » Wed Apr 24, 2019 12:17 am
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Forget conventional ways of solving math questions. For DS problems, the VA (Variable Approach) method is the quickest and easiest way to find the answer without actually solving the problem. Remember that equal numbers of variables and independent equations ensure a solution.

Note: Even though C is most likely to be an answer since we have two variables, D is likely to be the answer by Tip 1) because conditions 1) and 2) provide the same information.

Condition 1)
(x^2-6xy+9y^2)=0
=> (x-3y)^2 = 0
=> x -3y = 0
=> x = 3y
=> x/y = 3
Thus, condition 1) is sufficient.

Condition 2)
|x-3|+|y-1|=0
=> |x-3|+|y-1|=0
=> x=3 and y=1
So, x/y = 3/1 =3.
Thus, condition 2) is sufficient.

Therefore, D is the answer.
Answer: D
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