2-4 Additional Practice
Parallel and Perpendicular Lines

Determine whether this is parallel, perpendicular, or niether.
y=3x+5
-3x-y=9

y-7x=3
14x-2y=28

Respuesta :

Answer:

The first pair of lines is neither perpendicular not parallel. The second pair of lines is parallel.

Step-by-step explanation:

If a line is defined as

[tex]Ax+By+C=0[/tex]

Therefore the slope of the line is

[tex]m=\frac{-A}{B}[/tex]

Slope of parallel lines are equal. Product of slopes of perpendicular lines is -1.

In the first pair of lines,

[tex]y=3x+5[/tex]

It is a slope intercept form of a line, therefore the slope of the line is 3.

[tex]-3x-y=9[/tex]

This equation can be written as

[tex]0=9+3x+y[/tex]

Slope of the line is

[tex]m=\frac{-3}{1}=-3[/tex]

The slopes of both lines are not equal therefore the lines are not parallel. The product of their slopes is not -1, therefore the lines are not perpendicular.

In the second pair of lines,

[tex]y-7x=3[/tex]

This equation can be written as

[tex]y-7x-3=0[/tex]

Therefore the slope of the line is

[tex]m=\frac{7}{1}=7[/tex]

[tex]14x-2y=28[/tex]

This equation can be written as

[tex]14x-2y-28=0[/tex]

[tex]m=\frac{-14}{-2}=\frac{7}{1}=7[/tex]

Since the slopes of lines are equal, therefore the lines are parallel to each other.

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