GMAT question 122

I

ironsheep

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This question is from "GMAT Official Guide 2019 Quantitative Review".

"In the xy-plane, the points (c,d), (c,-d), and (-c, -d) are three vertices of a certain square. If c< 0 and d> 0, which of the following points is in the same quadrant as the fourth vertex of the square?" The answer is (3,5).

I think the answer is (-5,3) because this graph is that of a square and the fourth point should be in a quadrant that is different that the three given. Also, c is less than 0 and d is greater than 0. c equals -5, d equals 3.

What do you think of my reasoning and why?
 
Answer these questions to see why you are wrong:
1. What quadrant is (c, d) in? Remember that c is negative and d is positive.
2. What quadrant is (c, -d) in? Remember that c is negative and -d is negative (since d is pos)
3. What quadrant is (-c, -d) in? -c is positive or negative? -d is pos or neg?
 
Hello. The points listed in the multiple choices are not necessarily located at a vertex on the square (±3 and ±5 won't form a square.) Also, keep in mind that symbol c represents a negative number and the expression -c represents a positive number.

The point (c,d) is in Quadrant II because the x-coordinate is negative and the y-coordinate is positive.

The point (c,-d) is in QIII because the x-coordinate is negative and the y-coordinate is negative.

In what quadrant is (-c,-d) located?

?
 
Otis said:
Hello. The points listed in the multiple choices are not necessarily located at a vertex on the square (±3 and ±5 won't form a square.) Also, keep in mind that symbol c represents a negative number and the expression -c represents a positive number.

The point (c,d) is in Quadrant II because the x-coordinate is negative and the y-coordinate is positive.

The point (c,-d) is in QIII because the x-coordinate is negative and the y-coordinate is negative.

In what quadrant is (-c,-d) located?

?
Click to expand...
SNAP!!
 
So the fourth point should be (-c, d) because that is the only one missing. A negative, negative c is a positive number and d is already postive. So it would be (3,5)
 
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