Help on a Coordiate geometry problem

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Help on a Coordiate geometry problem

by crackgmat007 » Wed May 06, 2009 9:41 am

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Q: The graph of which of the following equations is a straight line that is parallel to line l in the figure below?
A. 3y � 2x = 0
B. 3y + 2x = 0
C. 3y + 2x = 6
D. 2y � 3x = 6
E. 2y + 3x = -6
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Last edited by crackgmat007 on Sat May 09, 2009 9:39 pm, edited 1 time in total.

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by ddoonie » Fri May 08, 2009 12:17 pm
If the answer is A, then this is how i got it...

Find slope of line L
y1-y2/x1-x2
2-0/0-(-3) = 2/3

Parallel line has same slope, so find equation with same slope..

A. 3y-2x = 0
3y=2x
y=(2/3)x

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by kic883 » Sat May 09, 2009 8:38 am
ddoonie wrote:If the answer is A, then this is how i got it...

Find slope of line L
y1-y2/x1-x2
2-0/0-(-3) = 2/3

Parallel line has same slope, so find equation with same slope..

A. 3y-2x = 0
3y=2x
y=(2/3)x
I got the same answer. agree with A

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crackgmat007 wrote:Q: The graph of which of the following equations is a straight line that is parallel to line l in the figure below?
A. 3y - 2x = 0
B. 3y + 2x = 0
C. 3y + 2x = 6
D. 2y - 3x = 6
E. 2y + 3x = -6
If two lines are parallel, then they have the SAME SLOPE.

The line passes through the points (0, 2) and (-3, 0)

Applying the slope formula, we get: Slope = (2 - 0)/(0 - -3)
= 2/3

Now take each equation of each line (in the answer choices) and rewrite it in slope y-intercept form: y = mx + b (where m = slope and b = y-intercept)

The rewritten equation that has m = 2/3, will be the correct answer....

A. 3y - 2x = 0...rewrite as y =(2/3)x + 0
DONE!
This line has a slope of 2/3, so it must be parallel with the given line.

Answer: A

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by Admin1 » Sun Sep 03, 2017 8:56 am
We can see in the figure that the line l passes through the points: (-3,0) and (0,2).

The slope of line l is given by the formula: (y2-y1) / (x2-x1).

Let's say that (x1,y1)= (-3,0) and (x2,y2)= (0,2). The slope of the line l is: (2-0) / (0- (-3)) = 2/3.

We want to pick from the options the equation whose graphic is parallel to the line l So, we have to pick the equation whose slope is 2/3 (because two lines are parallel if their slopes are the same).

Let's remember that: given a line with the equation Ax+By+C=0, the slope of the line is m=-A/B.

The slope of the equation 3y-2x=0 is m = -(-2)/3=2/3.

So, the answer is A.