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Posted by **Jamie** on Wednesday, June 17, 2009 at 1:42pm.

Find the slope for a line parallel to the given line

Find the slope for a line perpendicular to the given line

- Algebra -
**Reiny**, Wednesday, June 17, 2009 at 1:47pmchange to the form y = mx + b, the value of m will be the slope

5x - y = 10

-y = -5x + 10

y = 5x - 10

the slope is 5

perpendicular lines have slopes that are the opposite reciprocals of each other.

so if the first slope is 5, the slope of the perpendicular is -1/5

- Algebra -
**Jamie**, Wednesday, June 17, 2009 at 1:58pmSo is the slope of the given line 2.5? I don't need to know that, but just wanted to make sure. Thanks!

- Algebra -
**Reiny**, Wednesday, June 17, 2009 at 2:40pmyes, or 5/2

making the slope of the reciprocal - 2/5

- Algebra -
**Jamie**, Wednesday, June 17, 2009 at 2:45pmBut that is for the given line not the parallel or perpendicular one? So what I see is as follows and is correct?

a. For the Parallel slope we change to the form y = mx + b, and the value of m is the slope

5x - 2y = 10

-y = -5x + 10

y = 5x - 10

the slope is 5

m = 5

Why are we using -y? isn't it -2y? or is this ok? How do we conclude it's 5?

AND for this one

b. Find the slope for a line perpendicular to the given line.

Perpendicular lines have slopes that are the opposite reciprocals of each other.

So if the parallel line slope is 5, the slope of the perpendicular line is -1/5 because it is the reciprical?

I just wanna be sure I am understanding this correctly! Thanks for you time and help!

- Algebra -
**Reiny**, Wednesday, June 17, 2009 at 3:43pmYou are right, I copied the equation incorrectly

I apologize for the confusion

here is the correct version:

5x - 2y = 10

-2y = -5x + 10

y = (5/2)x - 5

the slope is 5/2

perpendicular lines have slopes that are the opposite reciprocals of each other.

so if the first slope is 5/2, the slope of the perpendicular is -2/5

to get the slope of the perpendicular to any given line

... flip the slope and change the sign

e.g. first slope : -5/9

slope of perp. is +9/5

e.g. first slope = +6

slope of perp. is -1/6

- Algebra -
**Breanna**, Wednesday, June 17, 2009 at 3:53pmIs this the slope to the parallel line and perpendicular line or for the given line of 5x – 2y = 10? I am a bit confused about this because I get 5/2 or 2 and 1/2 for the slope of the given line. Can you please explain further? Thanks!

- Algebra -
**Beth**, Wednesday, June 17, 2009 at 4:15pmI think I got it! Are the slopes of the given and parallel lines = ?

- Algebra -
**Breanna**, Wednesday, June 17, 2009 at 4:18pmBeth good job! I think this is correct. Lets see what the experts have to say about this!