Question

how do i find out if these two lines are perpendicular? please show me how to work the problem:
-4x+2y=12, x+2y=6

Answer 1

Do you know how to find the slope ?

Answer 2

yes

Answer 3

well maybe not

Answer 4

Okay, great! What are the slopes?

Answer 5

lol

Answer 6

Fine I'll tell you how :)

Answer 7

i get the y =mx+b? or is there another method that would make this easier?

Answer 8

thanks

Answer 9

No you got it! y=mx+b where 'm' is the slope and 'b' is the y-intercept.

Answer 10

ok, then what do i do to the problem? first i get them in the correct format? and then?

Answer 11

I'll do the first one and you do the second one.

-4x+2y=12

As you said you return it to the form y=mx+b

2y=4x+12
y=2x+6

And right we said that y=mx+b where 'm' is the slope ?

What do we have instead of m here ? 2 right ?

For the first one the slope is 2.

Get it ?

Answer 12

yes, the second is y=-1/2x+3, so then what

Answer 13

Yep! What is the slope ?

Answer 14

-1/2, now how do i know if they are perpendicular?

Answer 15

Correct, you know they are perpendicular when you multiply the slope together you get -1

-1/2*2=-1

So yes they are perpendicular.

Answer 16

so if they equal -1 when multiplied they are perp? then are they parallel if they slop is similar and the y intercept is different?

Answer 17

Yes! Don't worry about the y-intercept.

Answer 18

why not worry about the y intercept?

Answer 19

Because you won't use it to know if they are perpendicular or parallel.

Answer 20

so is a line parallel if it has the same slope always?

Answer 21

Yes!

Answer 22

oh, thanks

Answer 23

Anytime! =D