## formula for line parallel to another line

Simplificatation, evaluation, linear equations, linear graphs, linear inequalities, basic word problems, etc.
santaclaus
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### formula for line parallel to another line

Find a formula for the line parallel to the line y=20-4x and containing hte point (3,12)

stapel_eliz
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Find a formula for the line parallel to the line y=20-4x and containing hte point (3,12)
To learn about the relationships between parallel and perpendicular slopes, try this lesson on slope.

To learn how to use a point and a slope to find the equation for a line, try this lesson on line equations.

santaclaus
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Joined: Tue Mar 03, 2009 12:17 am
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### Re: formula for line parallel to another line

so, after the lesson I read, could I solve this by saying that -4 is the slope parallel? I don't know how to use the point (3 and 12) to think of an equation y=mx +b? or y-y1 = -4(x-x1) and if I solve, i get y-12 = -4x+12 and then get y= -4x +24????

stapel_eliz
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Joined: Mon Dec 08, 2008 4:22 pm
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so, after the lesson I read, could I solve this by saying that -4 is the slope parallel?
Yes; parallel lines have the same slope.
I don't know how to use the point (3 and 12) to think of an equation
Try using the methods explained and demonstrated in the lesson on straight-line equations (in the link provided earlier).
i get y-12 = -4x+12 and then get y= -4x +24????
I think you did the following:

. . . . .$m\, =\, -4\, \mbox{ and }\, (x_1,\, y_1)\, =\, (3,\, 12)$

. . . . .$y\, -\, y_1\, =\, m(x\, -\, x_1)$

. . . . .$y\, -\, 12\, =\, -4(x\, -\, 3)$

. . . . .$y\, -\, 12\, =\, -4x\, +\, 12$

. . . . .$y\, -\, 12\, +\, 12=\, -4x\, +\, 12\, +\, 12$

If so, your method is fine!