Question

from the line y=3x-10, find the equation of the line that is perpendicular to this line and goes through the point (9, -7)

Answer 1

Okay so what does a perpendicular slope have to be compared to the regular slope?

Answer 2

What is the slope in the original equation

Answer 3

It doesn't give an original slope, it just says to find a perpendicular line that will pass through point (9, -7)

Answer 4

@kayders1997

Answer 5

It does thought because the line is y=mx+b where m is slope and b is a y intercept

Answer 6

I posted the whole question up there, that's why im confused because they didn't give a slope
@kayders1997

Answer 7

Y=3x-10 is like saying 3 is the slope because y=mx where the m is 3 and m is slope your trying to find the perpendicular slope from that slope

Answer 8

okay, so can you walk me through it? I really stink at math @kayders1997

Answer 9

That's okay, so we know we have a slope of 3 you might want to thing of this as 3/1 when your finding the perpendicular slope you are doing the opposite sing of that original slope and flipping the fraction

Answer 10

So I can do an example of the process so you can see how it will work

Answer 11

that'd be awesome @kayders1997

Answer 12

Okay so say you have y=4x-3 you have a slope of 4 and you can think of it as 4/1 so you have to switch sign so you will have -4/1 now you witch the fraction so it would be -1/4 that would be the slope for the perpendicular line now you have to do the same process for this problem

Answer 13

okay, so how do i graph that as a perpendicular line?
@kayders1997

Answer 14

Were not quite there yet we still have a few steps did you get the perpendicular slope for the equation?

Answer 15

No, just that it has to go through (9, -7)
@kayders1997

Answer 16

Okay so do the process do you want me to go through it with you again but with the real equation?

Answer 17

Yes please, If you showed all thw work that'd be great :) @kayders1997

Answer 18

Do you want me to do the whole problem at once or step by step?

Answer 19

Step by step :)

Answer 20

Y=3x-10 so this is the slope for the perpendicular line, the real answer, so the slope is 3 so think of it as 3/1 so change the sign to a -3/1 and flip the fraction to -1/3 that is the perpendicular slope, does this make sense? :)

Answer 21

yeah :)

Answer 22

Good so now we go to the second part plugging the point (9,-7) into the point slope form do you know what that is?

Answer 23

So does that make the equation -1 over 3 x - 10?

Answer 24

Nope, we have to use the point

Answer 25

Do you know the point slope form equation?

Answer 26

yes

Answer 27

Okay so have your coordinate be (x1,y1) (9,-7) so what would youwrite in your equation?

Answer 28

If you dont know thats okay I can explain it :)

Answer 29

haha thanks I'd appreciate it

Answer 30

Okay so y-y1=m(x-x1) is the equation, so plug in(9,-7) and m into y1 x1 and m so you will have y--7=-1/3(x-9)
Remember the perpendicular slope is -1/3 not 3
Does this make sense?

Answer 31

If something isnt making sense just stop me

Answer 32

yeah, i got it. Thank you :) Can you help me with another question?

Answer 33

Sure I might have to eat soon though

Answer 34

okay cool,
Find the point M that cuts the segment with endpoints A(-10, -2) and b(7, 8) into the ratio 2:3

Answer 35

I don't know if I can help with this one I havent been in geometry in 2 years

Answer 36

haha yeah i haven't reviewed in a while so I'm stuck

Answer 37

I can maybe try later i gtg

Answer 38

okay thanks for your help :)

Answer 39

No problem :)