Question

Help please. Fan and medal.
Given the line 2x – 3y = 9 and the point (4, –1), find lines through the point that are


(a) parallel to the given line and
(b) perpendicular to it.

Answer 1

Have to tried plotting the function?

Answer 2

@Tommynaiter I still don't understand how to get the equations for the parallel and perpendicular lines.

Answer 3

Do oyu know th estraight line equation

y = mx+b ?

rewrite your equation so it looks like that

y = ??

Answer 4

its called slope intercept form btw

Answer 5

not estraight line equation

Answer 6

I know the form the equation is supposed to be in. I don't know how to convert it

Answer 7

all you need to do is isolate y

Answer 8

so, subtract x from both sides, and divide both sides by y's coefficient

Answer 9

@TheSavior

you need to subtract 2x from each side

then divide by 3

Answer 10

correction
divide by -3

Answer 11

-3 IS y's coeffeicient lol

Answer 12

Then y still wouldn't be isolated right?

Answer 13

why not?

Answer 14

oh never mind I see it now

Answer 15

so now I have y=-3-2x right?

Answer 16

No, move the x so that it is y=mx+b

Answer 17

ok so y=2x-(-3) but what now

Answer 18

and you didn't divide the -2 (x's coefficient also known as the slope, or m in this case) by -3

Answer 19

that's still not right.

Answer 20

well then idk

Answer 21

when you move a number, you do not change whether it is positive or negative. The 2x should still be negative

Answer 22

very close, it was y=-2x-3

Answer 23

Now to answer A, you have a point

Answer 24

in addition, you have the slope.

Answer 25

Did you learn point-slope form?

Answer 26

oh right, I forgot!

Answer 27

y= 2/3 x -3

Answer 28

I think she left

Answer 29

now I'm just lost

Answer 30

okay, it is still the same line, we just turned it into slope intercept form

Answer 31

do you know point slope form?

Answer 32

Kind of

Answer 33

All you need to know is the formula

Answer 34

since y-y1=m(x-x1),
you only need a slope and a random point

Answer 35

that is on the line

Answer 36

you have a slope and a point, so you can plug in the y coordinate for y1, the x coordinate for x1.

Answer 37

then plug in -2/3 for m

Answer 38

that is parallel, because the slope is the same

Answer 39

y-(-1)=-2/3(x-4)

Answer 40

right or no?

Answer 41

and what about the perpendicular line

Answer 42

what do you know about slope of perpendicular lines?

Answer 43

They have opposite slopes

Answer 44

not opposite

if one line has slope m then its perpendiclar has lope -1/m


so what is the slope of the perp to your line?

Answer 45

not a clue

Answer 46

you need to go and review your text about 'point intercept' formula

you need to know this before you can answer the question

Answer 47

parallel lines have SAME slope

perpendicular lines have slopes so that if one line has slope m then its perpendiclar has lope -1/m

Answer 48

but how do you do that when the slope is -2/3

Answer 49

your equatioon is

y = 2/3 x -3

so the slope is 2/3 (NOT -2/3) you can see that from your plot - the slope is positive

so what is -1/m if m=2/3

Answer 50

@MrNood I don't know how to do that without getting some great big decimal