Question

what is an equation for the line that passes through points (-1, -4) and (1, 4)? i need help with this?!

Answer 1

plug the points into slope formula

Answer 2

it says i have to write an equation in slope intercept form

Answer 3

so find the slope of that equation first.

Answer 4

1/4

Answer 5

Good!
Now, I would graph it,

Answer 6

so what is the y intercept?

Answer 7

it [passes through the origin.

Answer 8

im not sure

Answer 9

where on the line does x equal 0?

Answer 10

middle

Answer 11

yes, it is the (0,0) so that would mean what?

Answer 12

so its one?

Answer 13

the intercept? No!

Answer 14

oh sorry

Answer 15

Look at the line, find the point on it which is on the 0 x-axis.

Answer 16

Equation of line passing through two points is given as;

\[y-y_1= \frac{y_1-y_2}{x_1-x_2} (x-x_1)\]
Here (-1, -4) and (1, 4)?
x1= -1, x2= 1
y1= -4, y2= 4
plugging these values in the above equation we find;
\[y-(-4)= \frac{-4-4}{-1-1} [x-(-1)]\]
\[\rightarrow y+4= \frac{-8}{-2} [x+1]\]
\[\rightarrow y+4=4 (x+1) \rightarrow y+4=4x+4\]
\[\rightarrow y=4x+4-4 \rightarrow y=4x+0 \rightarrow y=4x\]
Hence y=4x is the required equation of the line.

@abbie

Answer 17

@dpasingh, we are guiding the asker, not giving out the work and answer!

Answer 18

@abbie do you understand?

Answer 19

im getting confused

Answer 20

Ok, where did you lose me?

Answer 21

im just going to skip this question

Answer 22

no, you can do it.

Answer 23

@abbie please don't skip it. Just tell me, I can redo it again.

Answer 24

What don't you understand?

Answer 25

no thnx never mind i get it

Answer 26

Nice to hear that!
it is y=4x
(as dpasingh said, so it is direct variation, in other words no y intercept.)
can you go to your next question please?)