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If x and y are integers and y=|x+3|+|4-x| , does y=7? (1) [#permalink]
 07 Aug 2008, 10:38
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If x and y are integers and y=|x+3|+|4-x| , does y=7?
(1) x<4
(2) x>-3
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Re: PowerPrep DS question [#permalink]
07 Aug 2008, 10:38
OA is C, but I have no clue why.
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Re: PowerPrep DS question [#permalink]
07 Aug 2008, 10:44
lumone wrote: OA is C, but I have no clue why. Enter X= -2 , -1, 0 , 1, 2, 3 in the expression you always get Y = 7
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Re: PowerPrep DS question [#permalink]
07 Aug 2008, 10:46
Y = (-x-3) + (-4+x)
Y= -7
i think option "1" is correct then
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Re: PowerPrep DS question [#permalink]
07 Aug 2008, 11:19
lumone wrote: If x and y are integers and y=|x+3|+|4-x| , does y=7?
(1) x<4
(2) x>-3 1) x<4 --> x-4<0 --> 4-x>0 --> |4-x| +ve |x+3| can be +ve or -ve (x=2 +ve X=-5 -VE) insuffcient (2) x>-3 --> x+3>0 means |x+3| = x+3 +ve but |4-x| can be -ve (-4+x) or +ve ( 4-x) so insufficient combine both 4-x>0 and x+3>0 both |x+3| , |4-x| lead positive values y= |x+3|+|4-x| = x+3+4-x =7 Clear C.
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Re: PowerPrep DS question [#permalink]
07 Aug 2008, 11:27
lumone wrote: If x and y are integers and y=|x+3|+|4-x| , does y=7?
(1) x<4
(2) x>-3 Remember that |a - b| is just the distance between a and b on the number line. Write the question as: y=|x - (-3)| + |4-x| In words, this says: "y is equal to the distance from x to -3 plus the distance from x to 4. Draw a number line, draw the points -3 and 4, and put x in the middle. If you add the two distances, you clearly get 7, the distance from -3 to 4. If x is less than -3 or larger than 4, the sum of the distances will be larger than 7. Easy to see if you draw the picture. So we need both statements: C.
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Re: PowerPrep DS question [#permalink]
07 Aug 2008, 11:47
lumone wrote: x2suresh wrote: lumone wrote: If x and y are integers and y=|x+3|+|4-x| , does y=7?
(1) x<4
(2) x>-3 1) x<4 --> x-4<0 --> 4-x>0 --> |4-x| +ve |x+3| can be +ve or -ve (x=2 +ve X=-5 -VE) insuffcient (2) x>-3 --> x+3>0 means |x+3| = x+3 +ve but |4-x| can be -ve (-4+x) or +ve ( 4-x) so insufficient combine both 4-x>0 and x+3>0 both |x+3| , |4-x| lead positive values y= |x+3|+|4-x| = x+3+4-x =7 Clear C. what's ve? +ve --> positive -ve --> negative
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Re: PowerPrep DS question [#permalink]
07 Aug 2008, 17:31
lumone wrote: If x and y are integers and y=|x+3|+|4-x| , does y=7?
(1) x<4
(2) x>-3 to solve this question lets consider three sets of values for x x<0------I x>0------II x=0------III in region I ,y= 3-x+4+x=7 in region II , y=3+x+4-x=7 in region III , y=3+4=7 hence always irrespective ofd any value of x we get y=7 why require I and II infact both are individually sufficient IMO D
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Re: PowerPrep DS question [#permalink]
07 Aug 2008, 17:32
farrukhiq wrote: Y = (-x-3) + (-4+x)
Y= -7
i think option "1" is correct then I dont agree with since |-x-3|=x+3
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Re: PowerPrep DS question
[#permalink]
07 Aug 2008, 17:32
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