Hi Two questions from GMAT prep s/w, looking for the best method to solve it:
#A) If X and Y are integers & Y=|X+3| + |4-X|, does Y=7?
(1) X<4
(2) X>-3
[Answer is C]
#B) If both X and Y are non-zero numbers, what is the value of Y/X?
(1) X=6
(2) Y^2=X^2
[Answer is E]
GMAT prep s/w Q abso value and Squares
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- Morgoth
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Y=|X+3| + |4-X|aditi_bc wrote:Hi Two questions from GMAT prep s/w, looking for the best method to solve it:
#A) If X and Y are integers & Y=|X+3| + |4-X|, does Y=7?
(1) X<4
(2) X>-3
[Answer is C]
Y = lX-(-3)l + l4-Xl
this can be deciphered as Y is equal to addition of distance between x and -3 and distance between 4 and x on a number line.
Therefore, if y=7, x has to be between -3 and 4
The question is basically asking -3<x<4 ?
Statement (1) & (2) gives us exactly that.
Thus, C is the answer.
Y/X#B) If both X and Y are non-zero numbers, what is the value of Y/X?
(1) X=6
(2) Y^2=X^2
[Answer is E]
statement (1) X=6, we dont know anything about Y. Insufficient.
statement (2) Y^2 = X^2
X^2/Y^2 = 1
X/Y = +1 OR -1
Insufficient.
Combining (1) & (2)
X=6
6/Y = -1
6/Y = +1
Insufficient.
Thus, E is the answer.
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Morgoth, could you please elaborate your approach to these expression?aditi_bc wrote:Thanks Morgoth!
Is there any other way of working with the expression Y=|X+3| + |4-X|?
How you deducted that it is the same as -3<x<4 ?
- Morgoth
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Here is the process:4meonly wrote:Morgoth, could you please elaborate your approach to these expression?aditi_bc wrote:Thanks Morgoth!
Is there any other way of working with the expression Y=|X+3| + |4-X|?
How you deducted that it is the same as -3<x<4 ?
Let the two points be -2 and 2
Let x is the distance between -2 and 2 = l-2-2l = 4 or l2-(-2)l = 4
if y is the point between -2 and 2
X = ly-(-2)l + l2-yl
X = ly+2l + l2-yl
for any value of y between the -2 and 2, X will always be 4
Let me know if you still have any doubts.