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Re: If m represents the slope of a line in the coordinate geom [#permalink]
Zarrolou wrote:
If m represents the slope of a line in the coordinate geometry plane, does the line intersect quadrant III?

1. \(|m|= m\)
So m is \(\geq{ 0}\). If m is 0, the line is straight, hence it can or cannot intersect the III quadrant.
Consider \(y=-100\) (yes) and \(y=100\) (no)

2. \(m^2=3m\)
\(m^2-3m=0\) so \(m=3\) or \(m=0\). If m=3, it will intersect the III quadrant, but if m=0 it can or cannot.

1+2) Since m=0 is common, both statements are still not sufficient


Two questions:

First, in #1 you said that if the slope is negative 100 it intersects III but in #2 you said if it is positive 3 it intersects III. Doesn't the sign change mean it intersect different quadrants?

Second, if both 1 and 2 share a single common value (in this case, 0) doesn't that mean we have a single, definitive answer?

Thanks!
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Re: If m represents the slope of a line in the coordinate geom [#permalink]
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If m represents the slope of a line in the coordinate geometry plane, does the line intersect quadrant III?

1. |m|= m
M>=0

The slope could be equal to zero in which case the line runs flat along the x axis and does not pass through QIII.

The slope could be equal to 5 in which case the line would pass through QIII at some point.
INSUFFICIENT

2. m^2=3m

M^2 - 3m = 0

m=0, m=3. As with above, if m=0 it will not pass through QIII but if m=3 then it will.
INSUFFICIENT

1+2
#1 tells us m>=0 and #2 tells us m=0 OR m=3 which is redundant when considering #1. Therefore, m may or may not pass through QIII.
INSUFFICIENT

(E)
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Re: If m represents the slope of a line in the coordinate geom [#permalink]
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WholeLottaLove wrote:
Zarrolou wrote:
If m represents the slope of a line in the coordinate geometry plane, does the line intersect quadrant III?

1. \(|m|= m\)
So m is \(\geq{ 0}\). If m is 0, the line is straight, hence it can or cannot intersect the III quadrant.
Consider \(y=-100\) (yes) and \(y=100\) (no)

2. \(m^2=3m\)
\(m^2-3m=0\) so \(m=3\) or \(m=0\). If m=3, it will intersect the III quadrant, but if m=0 it can or cannot.

1+2) Since m=0 is common, both statements are still not sufficient


Two questions:

First, in #1 you said that if the slope is negative 100 it intersects III but in #2 you said if it is positive 3 it intersects III. Doesn't the sign change mean it intersect different quadrants?

Second, if both 1 and 2 share a single common value (in this case, 0) doesn't that mean we have a single, definitive answer?

Thanks!


Please read this post: if-m-represents-the-slope-of-a-line-in-the-coordinate-geom-155176.html#p1241612

Next, when considering the statements we have that m=0, which means that the line is horizontal. The question is "does the line intersect quadrant III?" not what is the value of m. Horizontal line may or may not intersect quadrant III.

Hope it's clear.
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Re: If m represents the slope of a line in the coordinate geom [#permalink]
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WholeLottaLove wrote:
Zarrolou wrote:
If m represents the slope of a line in the coordinate geometry plane, does the line intersect quadrant III?

1. \(|m|= m\)
So m is \(\geq{ 0}\). If m is 0, the line is straight, hence it can or cannot intersect the III quadrant.
Consider \(y=-100\) (yes) and \(y=100\) (no)

2. \(m^2=3m\)
\(m^2-3m=0\) so \(m=3\) or \(m=0\). If m=3, it will intersect the III quadrant, but if m=0 it can or cannot.

1+2) Since m=0 is common, both statements are still not sufficient


Two questions:

First, in #1 you said that if the slope is negative 100 it intersects III but in #2 you said if it is positive 3 it intersects III. Doesn't the sign change mean it intersect different quadrants?

Second, if both 1 and 2 share a single common value (in this case, 0) doesn't that mean we have a single, definitive answer?

Thanks!


I think you are confusing the parts of the equation of the line.
\(y=Slope(=m)*X+k\)<== this is the standard for of a line.

These two lines have NO SLOPE (they are straight, horizontal, parallel to the x-axis) => m=0.
\(y=-100\) \(y=100\). y=-100 is a straight line that passes through the III and IV quadrant; y=100 passes through the I and II quadrant.
(refer to the image)

If we know that m=0 both y=100 and y=-100 are still valid.
Attachments

Im.JPG
Im.JPG [ 12.14 KiB | Viewed 23271 times ]

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Re: If m represents the slope of a line in the coordinate geom [#permalink]
Bunuel wrote:
WholeLottaLove wrote:
Zarrolou wrote:
If m represents the slope of a line in the coordinate geometry plane, does the line intersect quadrant III?

1. \(|m|= m\)
So m is \(\geq{ 0}\). If m is 0, the line is straight, hence it can or cannot intersect the III quadrant.
Consider \(y=-100\) (yes) and \(y=100\) (no)

2. \(m^2=3m\)
\(m^2-3m=0\) so \(m=3\) or \(m=0\). If m=3, it will intersect the III quadrant, but if m=0 it can or cannot.

1+2) Since m=0 is common, both statements are still not sufficient


Two questions:

First, in #1 you said that if the slope is negative 100 it intersects III but in #2 you said if it is positive 3 it intersects III. Doesn't the sign change mean it intersect different quadrants?

Second, if both 1 and 2 share a single common value (in this case, 0) doesn't that mean we have a single, definitive answer?

Thanks!


Please read this post: if-m-represents-the-slope-of-a-line-in-the-coordinate-geom-155176.html#p1241612

Next, when considering the statements we have that m=0, which means that the line is horizontal. The question is "does the line intersect quadrant III?" not what is the value of m. Horizontal line may or may not intersect quadrant III.

Hope it's clear.


Ahhh. It's been a while since I've done anything related to coordinate geometry (trying to nail modules down cold haha!) Now I remember. Thanks.
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Re: If m represents the slope of a line in the coordinate geom [#permalink]
This is an updated version of my original solution found above.

If m represents the slope of a line in the coordinate geometry plane, does the line intersect quadrant III?

1. |m|= m
M>=0

If m = 0 then it has no slope. However, it still may or may not pass through QIII. If y = 2 then it would be a flat line passing through QI and QII. If y = -2 then it would be a flat line passing through QIII and QIV. Furthermore, if the line did have a slope, it may or may not pass through QIII. For example, if it had a slope of 2 it would pass through QIII (assuming it has infinite length) but if the slope was negative it may not ever pass through QIII)
INSUFFICIENT

2. m^2=3m

M^2 - 3m = 0

m=0, m=3. If the slope is zero then it may or may not pass through QIII. We would need to know it's y coordinate to determine that. If the slope is positive 3, then it would pass through QIII
INSUFFICIENT

1+2
Both 1 and 2 tell us that the slope could be zero or greater than zero. If the slope is zero then it may or may not pass through QIII. If it is greater than zero it will. We cannot determine if it passes through QIII or not.
INSUFFICIENT

(E)
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Re: If m represents the slope of a line in the coordinate geom [#permalink]
Zarrolou wrote:
If m represents the slope of a line in the coordinate geometry plane, does the line intersect quadrant III?

1. \(|m|= m\)
So m is \(\geq{ 0}\). If m is 0, the line is straight, hence it can or cannot intersect the III quadrant.
Consider \(y=-100\) (yes) and \(y=100\) (no)

2. \(m^2=3m\)
\(m^2-3m=0\) so \(m=3\) or \(m=0\). If m=3, it will intersect the III quadrant, but if m=0 it can or cannot.

1+2) Since m=0 is common, both statements are still not sufficient


Hi Zarrolou,

St1 |m|= m can also be inferred as |-m|=|m|= m since |-m|=|m|

this implies m>/ 0 or m <0

Combining with statement 2 we get m=0 as common and again answer can be yes or no depending upon value of y.

Will the above interpretation of st1 will be correct.

thanks
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Re: If m represents the slope of a line in the coordinate geom [#permalink]
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mridulparashar1 wrote:
Zarrolou wrote:
If m represents the slope of a line in the coordinate geometry plane, does the line intersect quadrant III?

1. \(|m|= m\)
So m is \(\geq{ 0}\). If m is 0, the line is straight, hence it can or cannot intersect the III quadrant.
Consider \(y=-100\) (yes) and \(y=100\) (no)

2. \(m^2=3m\)
\(m^2-3m=0\) so \(m=3\) or \(m=0\). If m=3, it will intersect the III quadrant, but if m=0 it can or cannot.

1+2) Since m=0 is common, both statements are still not sufficient


Hi Zarrolou,

St1 |m|= m can also be inferred as |-m|=|m|= m since |-m|=|m|

this implies m>/ 0 or m <0

Combining with statement 2 we get m=0 as common and again answer can be yes or no depending upon value of y.

Will the above interpretation of st1 will be correct.

thanks
Mridul


No, that's not correct.

\(|m|=m\) implies that \(m\geq{0}\) ONLY. What does m>/ 0 or m <0 even mean? It gives all values possible, doesn't it?

Absolute value properties:

When \(x\leq{0}\) then \(|x|=-x\), or more generally when \(some \ expression\leq{0}\) then \(|some \ expression|={-(some \ expression)}\). For example: \(|-5|=5=-(-5)\);

When \(x\geq{0}\) then \(|x|=x\), or more generally when \(some \ expression\geq{0}\) then \(|some \ expression|={some \ expression}\). For example: \(|5|=5\).
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Re: If m represents the slope of a line in the coordinate geom [#permalink]
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My 2 cents for this long discussion.
statement 1= |M|=M
in this case m can be 0 or +ve or -ve
NS

Statement 2= m^2=3m
hence m can be 3 or 0 NS

Combining M can be +ve or 0 thus E is the correct answer.
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Re: If m represents the slope of a line in the coordinate geom [#permalink]
gmatpapa wrote:
If m represents the slope of a line in the coordinate geometry plane, does the line intersect quadrant III?

1. \(|m|= m\)
2. \(m^2=3m\)



Statement 1. \(|m|= m\)
Analyzing the modulus : |Any number|= either 0 or +
That implies the value of m can be either 0 or +
Now if the slope of a line is either 0 or +, it can intersect or not intersect Quadrant III.
As Slope = Change in y/change in X
Scenario A: if ^y =+ and ^X=+, slope =+ ; Slope will intersect
Scenario B: if ^y =- and ^X=-, slope =+ ; Slope will intersect
Scenario C: if ^y =0 and ^X=-, slope =0 ; Slope will not intersect

So, It is not sufficient.

Statement 2. \(m^2=3m\)[/quote]
This statement also implies m is either + or 0 as product of a positive no. and a variable is equal to a square number.
Therefore again it is a restatement of earlier 1. So, It is also not sufficient.

Therefore , Answer E.
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If m represents the slope of a line in the coordinate geom [#permalink]
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gmatpapa wrote:
If m represents the slope of a line in the coordinate geometry plane, does the line intersect quadrant III?

1. \(|m|= m\)
2. \(m^2=3m\)


Target question: Does the line intersect quadrant III?
Jump straight to...

Statements 1 and 2 combined
Here are two scenarios that satisfy BOTH statements:
Case a: m = 3

In this case, the answer to the target question is YES, the line DOES intersect quadrant III

Case b: m = 0.

In this case, the answer to the target question is NO, the line does NOT intersect quadrant III

Since we cannot answer the target question with certainty, the combined statements are NOT SUFFICIENT

Answer: E

Originally posted by BrentGMATPrepNow on 21 Nov 2018, 08:15.
Last edited by BrentGMATPrepNow on 14 Sep 2020, 08:22, edited 1 time in total.
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Re: If m represents the slope of a line in the coordinate geom [#permalink]
gmatpapa wrote:
If m represents the slope of a line in the coordinate geometry plane, does the line intersect quadrant III?

1. \(|m|= m\)
2. \(m^2=3m\)


Hey guys,

it is probably obvious to the most of you, but why can't we just reduce the equation in 2 by m and have m = 3? Could it be possible if the stem mentioned any additional information?

Cheers
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Re: If m represents the slope of a line in the coordinate geom [#permalink]
Official Explanation:
If a line has a positive slope, then it must go through quadrants I and III in the coordinate geometry plane. Once that is established, this problem is more of a positive/negative number properties question. In other words, can the sign of m be determined from the information in the statements. Statement (1) guarantees that m is either positive OR zero. If a line has a slope of zero, then it is a horizontal line such as y = 5 which does not go through quadrant III. However, it could also be a line with a positive slope that does go through quadrant III so statement (1) is not sufficient. Statement (2) is a quadratic equation with two solutions. Setting all terms equal to 0, it is shown that m2 - 3m = 0 or m(m - 3) = 0 and m = 3 or 0. Again, this information is not sufficient because m could be positive or zero, yielding the same possibilities as statement (1). Putting the statements together, there is still ambiguity of whether m is 0 or positive, so the answer is E, both statements together are not sufficient.
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Re: If m represents the slope of a line in the coordinate geom [#permalink]
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