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# In the xy-plane, line l passes through the point (-7, k). What is the

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Re: In the xy-plane, line l passes through the point (-7, k). What is the [#permalink]
please tell me where i am wrong ?

line passes thru (4,0) and (-7,k)
we can calculate m = k-0/-7-4
m= -k/11

now using the slope we can write the equation as -

y=mx+ c
or y = -k/11x + c

points on line should satisfy equation : -
so putting y as k and x as -7 cant we get the value of C???

Please explain on this where am i going wrong
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Re: In the xy-plane, line l passes through the point (-7, k). What is the [#permalink]
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rohitkumar77 wrote:
In the xy-plane, line l passes through the point (-7, k). What is the value of the y-intercept of line l ?

(1) The x-intercept of line l is 4.

(2) Line l and line n are parallel and the equation of line n is y=x+5

please tell me where i am wrong ?

line passes thru (4,0) and (-7,k)
we can calculate m = k-0/-7-4
m= -k/11

now using the slope we can write the equation as -

y=mx+ c
or y = -k/11x + c

points on line should satisfy equation : -
so putting y as k and x as -7 cant we get the value of C???

Please explain on this where am i going wrong

For (1) we have the following:

The point (-7, k) can be anywhere on red line, giving different lines passing through (-7, k) and (4, 0), which will give different y-intercept of line l.

Hope it's clear.
Attachment:

1.png [ 4.06 KiB | Viewed 13138 times ]
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Re: In the xy-plane, line l passes through the point (-7, k). What is the [#permalink]
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Bunuel wrote:
In the xy-plane, line l passes through the point (-7, k). What is the value of the y-intercept of line l ?

(1) The x-intercept of line l is 4.

(2) Line l and line n are parallel and the equation of line n is y=x+5

y=mx+b; y-intercept when x=0, y=0+b, y=b, what is b=?
(-7,k): y=mx+b, k=-7m+b, b=k+7m

(1) The x-intercept of line l is 4. insufic

x-intercept when y=0: 0=4m+b, b=-4m

(2) Line l and line n are parallel and the equation of line n is y=x+5 insufic

parallel lines have the same slope: m_n=m_l=1

(1&2) sufic

b=-4m=-4(1)=-4

Ans (C)
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Re: In the xy-plane, line l passes through the point (-7, k). What is the [#permalink]
Bunuel wrote:
In the xy-plane, line l passes through the point (-7, k). What is the value of the y-intercept of line l ?

(1) The x-intercept of line l is 4.

(2) Line l and line n are parallel and the equation of line n is y=x+5

Kudos for a correct solution.

Analyzing the question:

We are not really given any information so we would still like two pieces of information to confirm a line.

Statement 1:
This is one piece of information, we need another piece. Insufficient.

Statement 2:
The slope is 1. This is just one piece of information, we need another piece. Insufficient.

Combined:
Now we have two pieces that are both meaningful, we can confirm a line. Sufficient.

Ans: C
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Re: In the xy-plane, line l passes through the point (-7, k). What is the [#permalink]
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Re: In the xy-plane, line l passes through the point (-7, k). What is the [#permalink]
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