Hi all,
Is 2<x<4?
1) x"2-5x+6<0
2)5x"2-25x>0
The answer is D which means both are sufficient...I don't understand why 2 is enough.
Thank you.
Inequalities....help plz
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Here we are looking for a yes/no for question Is 2<x<4
From 1
(x-2)(x-3)<0
so 2<x<3...
hence ans for Is 2<x<4--yes
From 2
5x(x-5)>0
or x(x-5)>0
so x and x-5 should have same sign .Hence the values of x which will satisfy this are x<0 and x>5
so x cannot have a value between 2 and 4
hence ans for Is 2<x<4--no
since we can definitely give an answer for 'Is 2<x<4? ' from both statements independently
Ans is option D
From 1
(x-2)(x-3)<0
so 2<x<3...
hence ans for Is 2<x<4--yes
From 2
5x(x-5)>0
or x(x-5)>0
so x and x-5 should have same sign .Hence the values of x which will satisfy this are x<0 and x>5
so x cannot have a value between 2 and 4
hence ans for Is 2<x<4--no
since we can definitely give an answer for 'Is 2<x<4? ' from both statements independently
Ans is option D
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What is the source? Findings from the two statements would never contradict on real GMAT.[email protected] wrote:Hi all,
Is 2<x<4?
1) x"2-5x+6<0
2)5x"2-25x>0
The answer is D which means both are sufficient...I don't understand why 2 is enough.
Thank you.
The mind is everything. What you think you become. -Lord Buddha
Sanjeev K Saxena
Quantitative Instructor
The Princeton Review - Manya Abroad
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Sanjeev K Saxena
Quantitative Instructor
The Princeton Review - Manya Abroad
Lucknow-226001
www.manyagroup.com
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liferocks wrote:Here we are looking for a yes/no for question Is 2<x<4
From 1
(x-2)(x-3)<0
so 2<x<3...
hence ans for Is 2<x<4--yes
From 2
5x(x-5)>0
or x(x-5)>0
so x and x-5 should have same sign .Hence the values of x which will satisfy this are x<0 and x>5
so x cannot have a value between 2 and 4
hence ans for Is 2<x<4--no
since we can definitely give an answer for 'Is 2<x<4? ' from both statements independently
Ans is option D
i do not get your answer, correct me if i am wrong please but:
statement 1: x^2-5x+6 < 0 => (x-3)(x-2) < 0 => x<3 or x<2 ... this is insuffient, isn't it?
statement 2: 5X^2-25X > 0 => 5x(x-5) > 0 => x>0 or x>5 ... this is insufficient!
from the statements above it's hard to tell if x is between 2 and 4 (i.e. 2<x<4).
i think the asnwer is (E)
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these two inferences are in correct.[email protected] wrote: statement 1: x^2-5x+6 < 0 => (x-3)(x-2) < 0 => x<3 or x<2 ... this is insuffient, isn't it?
statement 2: 5X^2-25X > 0 => 5x(x-5) > 0 => x>0 or x>5 ... this is insufficient!
(x-3)(x-2) < 0 range of values of x is 2<x<3 for any other value the inequality will not satisfy.You can pickup any value and check
Similarly if 5x(x-5) > 0 range of values of x is x<0 and x>5..any value from 0 to 5 will not satisfy the inequality.you can pickup any value and verify this.
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(x-3)(x-2) < 0===> if x-3<0 then x-2>0 or if x-2<0 then x-3>0 an invalid condition===> 2<x<3 the only condition will satisfy the inequality[email protected] wrote:liferocks wrote:Here we are looking for a yes/no for question Is 2<x<4
From 1
(x-2)(x-3)<0
so 2<x<3...
hence ans for Is 2<x<4--yes
From 2
5x(x-5)>0
or x(x-5)>0
so x and x-5 should have same sign .Hence the values of x which will satisfy this are x<0 and x>5
so x cannot have a value between 2 and 4
hence ans for Is 2<x<4--no
since we can definitely give an answer for 'Is 2<x<4? ' from both statements independently
Ans is option D
i do not get your answer, correct me if i am wrong please but:
statement 1: x^2-5x+6 < 0 => (x-3)(x-2) < 0 => x<3 or x<2 ... this is insuffient, isn't it?
statement 2: 5X^2-25X > 0 => 5x(x-5) > 0 => x>0 or x>5 ... this is insufficient!
from the statements above it's hard to tell if x is between 2 and 4 (i.e. 2<x<4).
i think the asnwer is (E)
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:thephoenix wrote:(x-3)(x-2) < 0===> if x-3<0 then x-2>0 or if x-2<0 then x-3>0 an invalid condition===> 2<x<3 the only condition will satisfy the inequality[email protected] wrote:liferocks wrote:Here we are looking for a yes/no for question Is 2<x<4
From 1
(x-2)(x-3)<0
so 2<x<3...
hence ans for Is 2<x<4--yes
From 2
5x(x-5)>0
or x(x-5)>0
so x and x-5 should have same sign .Hence the values of x which will satisfy this are x<0 and x>5
so x cannot have a value between 2 and 4
hence ans for Is 2<x<4--no
since we can definitely give an answer for 'Is 2<x<4? ' from both statements independently
Ans is option D
i do not get your answer, correct me if i am wrong please but:
statement 1: x^2-5x+6 < 0 => (x-3)(x-2) < 0 => x<3 or x<2 ... this is insuffient, isn't it?
statement 2: 5X^2-25X > 0 => 5x(x-5) > 0 => x>0 or x>5 ... this is insufficient!
from the statements above it's hard to tell if x is between 2 and 4 (i.e. 2<x<4).
i think the asnwer is (E)
i still do not get it but it's fine. thanks.
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I guess what Mogorosi is questioning is,
Given that (x-2)(x-3)< 0 , then why not say ( just as you would for an equation) , either (x-2)< 0 or (x-3)< 0 but rather (x-2)>0 and (x-3)<0 ...and ultimately 2<x<3. I know this creating a mental graph but that not going to be possible here. Is there a general rule?
Given that (x-2)(x-3)< 0 , then why not say ( just as you would for an equation) , either (x-2)< 0 or (x-3)< 0 but rather (x-2)>0 and (x-3)<0 ...and ultimately 2<x<3. I know this creating a mental graph but that not going to be possible here. Is there a general rule?
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Hey Haress, mogorosi
Technically you are correct to think that if a product of two factors is positive, either factor could be positive and the other negative. However in this case we don't need to worry about the possibility that (x-2) is negative and (x-3) is positive.
(x-2)(x-3) is negative, so one factor must be positive and the other negative. Because (x-2) is greater than (x-3) for any value of x*, (x-2) must be the positive factor and (x-3) must be the negative factor.
x-2>0 --> x > 2
x-3<0 ---> x < 3
Merge the two to get 2<x<3
Does that make sense?
-Patrick
*To compare x-2 to x-3, subtract x from both sides and you get -2 vs. -3. The left is greater than the right.
Technically you are correct to think that if a product of two factors is positive, either factor could be positive and the other negative. However in this case we don't need to worry about the possibility that (x-2) is negative and (x-3) is positive.
(x-2)(x-3) is negative, so one factor must be positive and the other negative. Because (x-2) is greater than (x-3) for any value of x*, (x-2) must be the positive factor and (x-3) must be the negative factor.
x-2>0 --> x > 2
x-3<0 ---> x < 3
Merge the two to get 2<x<3
Does that make sense?
-Patrick
*To compare x-2 to x-3, subtract x from both sides and you get -2 vs. -3. The left is greater than the right.