If |x+2|=4, what is the value of x?
(1) x^2 ≠4;
(2) x^2 = 36;
I understand why statement (2) is sufficient, but I don't see how the statement (1) could be sufficient.
The answer is D
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hi
according to the problem, the value of x could be x=2 if x>=-2, or x could be x=-6 if x<-2
(1) says that x does not equal 2, or -2, so the only value of x left is x=-6
as |-6+2|=|-4|=4
1 st is also suff
according to the problem, the value of x could be x=2 if x>=-2, or x could be x=-6 if x<-2
(1) says that x does not equal 2, or -2, so the only value of x left is x=-6
as |-6+2|=|-4|=4
1 st is also suff
- deight
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I can't seem to remember how to solve the equation |x+2|=4. I know, it's something simple, but it doesn't ring the bell. Isn't it a system of equations:
If x+2>0, then x+2=4
or
If x+2<0, then ???
Could you please remind me how to solve this equation?
Thank you in advance
If x+2>0, then x+2=4
or
If x+2<0, then ???
Could you please remind me how to solve this equation?
Thank you in advance
- Brian@VeritasPrep
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Hey deight,
Great question - absolute value questions seem to look a lot trickier than they really need to be.
Think about it this way: If the absolute value of x is 4, then that means that x is either 4 or -4, right?
Well, if the absolute value of (x + 2) is 4, then:
x + 2 = 4
or
x + 2 = -4
Probably the most natural way to approach these is just to remember that each absolute value "interior" has two solutions - the positive and negative value. So just treat that "interior" of the absolute value bracket as two different problems and you'll find both solutions.
Here, x + 2 = -4 is the negative option, meaning that x = -6.
Great question - absolute value questions seem to look a lot trickier than they really need to be.
Think about it this way: If the absolute value of x is 4, then that means that x is either 4 or -4, right?
Well, if the absolute value of (x + 2) is 4, then:
x + 2 = 4
or
x + 2 = -4
Probably the most natural way to approach these is just to remember that each absolute value "interior" has two solutions - the positive and negative value. So just treat that "interior" of the absolute value bracket as two different problems and you'll find both solutions.
Here, x + 2 = -4 is the negative option, meaning that x = -6.
Brian Galvin
GMAT Instructor
Chief Academic Officer
Veritas Prep
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GMAT Instructor
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Veritas Prep
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- deight
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Thank you, Brian!
It's a great way to think about the problems with absolute values.
Now I have just another question. If we solve the original equation, we get two answers (2 and -6), but it's not sufficient enough (for GMAT), because we want to have a single solution, right?
It's a great way to think about the problems with absolute values.
Now I have just another question. If we solve the original equation, we get two answers (2 and -6), but it's not sufficient enough (for GMAT), because we want to have a single solution, right?
- Brian@VeritasPrep
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Exactly right, deight - to be sufficient a statement must yield EXACTLY ONE answer to the question. So if it asks:
What is the value...
You need to be able to arrive at only one answer.
And if it asks a Yes/No...
You need the answer to be ALWAYS Yes or ALWAYS No - you can't have any room for doubt.
What is the value...
You need to be able to arrive at only one answer.
And if it asks a Yes/No...
You need the answer to be ALWAYS Yes or ALWAYS No - you can't have any room for doubt.
Brian Galvin
GMAT Instructor
Chief Academic Officer
Veritas Prep
Looking for GMAT practice questions? Try out the Veritas Prep Question Bank. Learn More.
GMAT Instructor
Chief Academic Officer
Veritas Prep
Looking for GMAT practice questions? Try out the Veritas Prep Question Bank. Learn More.