Question

Help? Please and thank you! What is the y coordinate of the y−intercept of the line that passes through the points
(−3, −1) and (1, 7)?

Answer 1

-3 -1
1 7

Answer 2

You have to find the slope of the line!

Answer 3

Slope is...\[\frac{ RISE }{ RUN }\]

Answer 4

Lagging is my life.

Answer 5

would that be equal to 1/2 for slope? or no?

Answer 6

Right:)

Answer 7

Well, what is my question asking for? the y coordinate?

Answer 8

Little confused.-.

Answer 9

Yes! To find where the line crosses the Y axes!

Answer 10

-2, 0? Random guess. Lol

Answer 11

\[y – y _{1} = m(x – x _{1})\]

Answer 12

Now using that formula I gave you plug in one of the Points that are given and solve for y.

Answer 13

-1 + 7 = m(-3 + 1)

Answer 14

- 7*

Answer 15

Not exactly...Only use one set of points and plug it into the y and x with a tiny 1...

Answer 16

More like...
y+1= M(x+3)

Answer 17

And M means slope so plug that in too!

Answer 18

y + 1 = 1/2(x + 3)

Answer 19

Yup, now solve for Y.

Answer 20

y = 1/2x + 1/2 ?

Answer 21

Yes:)

Answer 22

This form is call slope intercept form. To find y plug in 0 for X.

Answer 23

y = 1/2(0) + 1/2 y = 1/2 ?

Answer 24

(0,1/2)

Answer 25

Now, this will be tricky to put in the written response, because fractions turn from 1/2 to 12. Lol. Should I just put 0.5?

Answer 26

Wait...before you write it lets check it...cause something doesnt seem right...

Answer 27

I feel like it should be a whole number, my teacher said it should be for these ones.

Answer 28

I think is should be (0,5)...

Answer 29

@mathstudent55 Maybe they know if we did anything wrong.

Answer 30

I figured out!

Answer 31

@Luigi0210

Answer 32

The slope is 2!

Answer 33

we have to redo that with the slope of 2.

Answer 34

Because its Y/X not X/Y.

Answer 35

OpenStudy is lagging for me.

Answer 36

Its okay! it is (0,5)

Answer 37

\[y+1=2(x+3)\]

Answer 38

\[y=2x+5\]

Answer 39

@Luigi0210 I really need to know if he's right. I'm so confused.

Answer 40

Sorry for confusing you...:(

Answer 41

http://www.webmath.com/_answer.php
Its right, check...

Answer 42

Only if OpenStudy was a real person...

Answer 43

So you're just looking for the y-coordinate of the y intercept?

Answer 44

Yes.

Answer 45

Well you know that the y-intercept is when x=0 right?

Answer 46

Yes, but now I don't even know what the slope is anymore. 1/2 or 2 or 5 lol.

Answer 47

Slope is:
\[m=\frac{y2-y1}{x2-x1}\]

Answer 48

-3, -1 1, 7

Answer 49

-1 - 7
------
-3 - 1 ?

Answer 50

Just plug them in and solve.
and either way works, you get the same answer

Answer 51

-8
--
-4 ?

Answer 52

Yup, making the slope 2.
Now we plug that information into the point-slope formula:
y-y1=m(x-x1)

Answer 53

Open was right so far, except for the slope

Answer 54

y - 1 = 2(x - 7) ?

Answer 55

Yea, not just distribute.

Answer 56

*now

Answer 57

y = 2x - 13?

Answer 58

Yup!