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how do you write two equations that represent parallel lines? also how do u write equation representing a perpendicular line?

2007-12-24 08:16:27 · 6 answers · asked by Anonymous in Science & Mathematics Mathematics

6 answers

Parallel lines (same slopes)
y = mx + b
y = mx + c

For example:
y = 3x + 2
y = 3x + 5

Perpendicular lines (slopes are negative reciprocals)
y = mx + b
y = (-1/m)x + c

For example:
y = 3x + 2
y = (-1/3)x + 4

2007-12-24 08:21:52 · answer #1 · answered by Puzzling 7 · 3 1

For two parallel lines, coefficients of x and y are the same, the constant may or may not be the same.

eg

2x+3y=4

2x+3y=9

For the equation of a line perpendicular to another line, interchange coefficients of x and y and negate the coeffitcient of y after interchanging, and introduce some constant.

eg:

for 2x-3y=6, perpendicular line is of the form,

-3x-2y=k

value of k can be found by substituting any point like (1,2) that lies on the perpendicular line.

:)

2007-12-24 08:26:56 · answer #2 · answered by ♣♠The Boss♠♣ 3 · 0 1

2 equations w/ a parallel lines will ALWAYS have the same slope

2 equations w/ perpendicular lines will ALWAYS have slopes, when multiplied, will be the negative reciprocal

e.g. y = -4x - 5 and y = -4x+8
the slope (m) is -4
the slopes are the same
the lines are parallel

e.g. y = -4x - 5 and y = 1/4x +8
the slope (m) is -4 x -1= 4 and find the reciprocal
which is 1/4

2007-12-24 08:23:16 · answer #3 · answered by kd3223 2 · 1 1

The equation for a line has the form of:

y=mx + b

if two lines are parallel, then the m terms for both lines will be identical, but the b terms will be different.

so the following lines are parallel,

y =3 x + 4
y= 3x - 4
y= 3x

2007-12-24 08:24:13 · answer #4 · answered by WhatWasThatNameAgain? 5 · 0 1

parallel line equations have the same slope such as y=3x+2 and y=3x-9
Perpendicular lines have slopes that are the inverse and opposite signs such as y=4x+2 and y=-1/4x+10

2007-12-24 08:24:09 · answer #5 · answered by Sarah L 2 · 1 1

for parallel, write an equation then place || inbetween
for perp, place a + inbetween

2007-12-24 08:21:37 · answer #6 · answered by csd 3 · 0 4

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