How can I find the slope and y intercept of a line, without graghing, when all I am given is two points?

Question

Like, if I'm given (-7, 10) and (-3,2), how would I use that information alone to solve for the y intercept and the slope?

Answer 1

the slope m=(y2-y1)/(x2-x1)

m=2-10/-3-(-7)= - 8/4 = - 2

y=mx+b (m is the slope, b is the y-intercept)

If you replace y with 2 and x with -3, you will get:

2=-2(-3)+b

2=6+b

b=-4

So slope=-2, y-intercept=- 4

For a similar problem explained in a video, click here and play the first video:

http://www.math-videos-online.com/free-math-homework-help.html

Answer 2

Change in y / Change in x = slope
Then using y=m(x) + b plug in slope for m and one point (x,y), solve for b. In this case

m = -2
b = -4

you can then use the other point to check your answer by pluging in only the x and solving for y

Answer 3

y2-y1 over x2-x1 will give you the slope

2-10
___
-3-(-7)

-8
___
4
Slope is -2.
y= -2x

For the y-intercept I don't know... You can draw it on paper and include those points without a calculator.

Answer 4

Well, I can't give you the answer since this is for homework, but remember: y=mx+b.

Just kidding. That is all I remember from algebra. hah. Good luck. :)

Answer 5

What Brittany said.

Answer 6

my brain hurts :/