L1 thru (-4,0), (0,6): find slope of parallel lines, draw L2  TOPIC_SOLVED

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L1 thru (-4,0), (0,6): find slope of parallel lines, draw L2

Postby cau on Sat Apr 11, 2009 2:14 am

draw L1 through (-4,0) and (0,6). What is the slope of any ling parrellel to L1? Draw L2 through the origin and parrell to L1.
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Re: graphing problem

Postby Martingale on Sat Apr 11, 2009 2:41 am

cau wrote:draw L1 through (-4,0) and (0,6). What is the slope of any ling parrellel to L1? Draw L2 through the origin and parrell to L1.


try looking at http://www.purplemath.com/modules/slope.htm and see what you can get
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Postby stapel_eliz on Sat Apr 11, 2009 11:47 am

cau wrote:draw L1 through (-4,0) and (0,6). What is the slope of any ling parrellel to L1? Draw L2 through the origin and parrell to L1.

You've already been provided a link to learn how to find the slope of the line L1 through the points (-4, 0) and (0, 6), and the lesson at that link will also explain how the slope of L1 relates to the slopes of all lines parallel to L1.

In case you're not familiar with how to plot points and draw lines (and this is why you haven't indicated having been able to get started on any portion of the exercise), you can learn about the x,y-plane here. This lesson will explain, for instance, that the point (-4, 0) is found by starting at the "origin" (the place where the two arrow-lines, or "axes", cross), moving left by four units, going up zero units, and then drawing a dot.

To learn how to graph lines from the slope (and the y-intercept), try here. To learn how to graph lines in general, try here. :wink:

Once you have learned the basic terms and techniques, please attempt the exercise. If you get stuck, you will then be able to reply with a clear listing of your work and reasoning so far. Thank you! :D
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Re: L1 thru (-4,0), (0,6): find slope of parallel lines, draw L2  TOPIC_SOLVED

Postby kinsey on Mon Apr 13, 2009 12:34 am

To find the slope of the line that passes through points (-4,0) and (0,6) you should use the slope formula, y2-y1/x2-x1.

To find the slope of L1 in particular:
6-0/0-(-4)
This will give you the slope:
6/4 which can then be reduced to 3/2

To complete the equation of the line you must also solve for the y-intercept
To find the y-intercept you must use the equation: y=mx+b where m is the slope and b is the y-intercept

L1's equations thus far is y=3/2x+b
to find b you must plug in an ordered pair for the x and y in the equation
for example:
y=3/2x+b
6=(3/2)(0)+b
6=b

Your equation for L1: y=3/2x+6

To graph this line you should plot the points and connect them with a straight, solid line.

To find the slope of the parallel lines you must first learn that parallel lines to any given line always have the same slope.
Thus, any line parallel to L1 (y=3/2x+6) would have the slope 3/2

To draw L2 through the origin you must plug in the ordered pair (0,0) in the equation y=3/2x+b to find b for the equation of L2

y=3/2x+b
0=(3/2)(0)+b
0=b

The equation of L2: y=3/2x

To find points to aid you in graphing L2 you can plug in numerical values for x and then solve for y
for example:
if X=2 then Y=3
if X=4 then Y=6

to graph plot these points on a coordinate plane and connect them with a solid straight line
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