Question

Write the slope-intercept equation for the line that passes through (1, -9) and (3, -1).

Answer 1

Insert each point one at a time into the formula y = mx + b creating two equations:

-9 = m + b
-1 = 3m + b

Next isolate b in each equation:

b = -9 - m
b = -1 - 3m

Divide both sides of the first equation by -1 to get

-b = 9 + m
b = -1 - 3m

Combine both equations together to get

0 = 8 -2m

Add 2m to both sides to get

2m = 8

Finish solving for m. Let me know what you get.

Answer 2

You have to solve for m and b to get the slope and y-intercept.

Answer 3

2m+8=10 or do i have to *

Answer 4

:/

Answer 5

Do you know how to isolate a variable in an equation?

Answer 6

no

Answer 7

I'm sorry to hear that. That's basic algebra. You should know how to do it.

Answer 8

you have to find slope first, which you can do when given 2 points. Do you know that formula?

Answer 9

You're supposed to divide both sides by 2 to get

m = 8/2
m = 4

Answer 10

m = the slope of the line you're trying to find

Answer 11

Now if you substitute m back into one of the original equations above, you can get b:

b = -9 - m
b = -9 - 4

@amber517 can you solve for b here?

Answer 12

ok from what i was look at top i massed up and thought you + 2m to 8 and

Answer 13

Can you solve for b?

Answer 14

Tell me what b equals

Answer 15

:/

Answer 16

would the b=1 and b=3

Answer 17

Did you even read anything I posted? :/

Answer 18

yes

Answer 19

Amber - you can find slope by finding the change in y divided by the change in x.
Once you find the slope (m) you can then put it in the slope-intercept form. y-y1=m(x-x1). Which is what they are asking for. =)

Answer 20

@mmencer, we were getting there. All @amber517 had to do was find m and b

The slope intercept form is obviously y = mx + b

Answer 21

@mmencer, what you posted is called the point-slope form

Answer 22

@mmencer, you're confused.

Answer 23

i'm confused

Answer 24

http://www.purplemath.com/modules/strtlneq.htm

Answer 25

I'll leave you two to finish...sorry to interrupt. Good luck, Amber.

Answer 26

so i'm tryin to understand this i'm dum when it comes to algebra

Answer 27

-9 = m + b
-1 = 3m + b
when you did this what happen to the other 1

Answer 28

shouldn't it be -9=1m+b -1=3m+b

Answer 29

m = 1m

It's the same thing

Answer 30

Remember, anything times 1 is itself

Answer 31

1 x 9 = 9
1 x m = m

Answer 32

ok ok would it be -13

Answer 33

b=-13

Answer 34

m=(y2-y1)/(x2-x1)
m=(-1--9)/(3-1)
m=8/2
m=4
y=mx+b
-1=4(3)+b
-1=12+b
-13=b
y=4x-13

Answer 35

Yes, finally

Answer 36

Well, you didn't do it the way I wanted you to do it, but you did it.