Question

Write an equation in slope intercept form of the line that passes through (4, 1) and (5, -1).

y = -4x + 1

y = -1/2 x + 9

y = 4x + 1

y = -2x + 9

Answer 1

first we need to find the slope
\[slope=\frac{ y2-y1 }{ x2-x1}\]
\[\frac{ -1-1 }{ 5-4 }\]

Answer 2

-2/1 slope

Answer 3

can that be simplified?

Answer 4

no

Answer 5

yes it can :) anything whats -2 divided by 1?

Answer 6

you can make a small 2 by x, and by y,

say `y_2` or `x_2`

Answer 7

-2

Answer 8

now lets put it in
\[y-y_1=m(x-x_1)\]
using the coordinates (4,1)
and because the slope is -2 our m is -2

Answer 9

-1-1 = -2 (5-4)

Answer 10

leave the first x and y alone
\[y-1=-2(x-4)\]

Answer 11

can you distribute our slope?

Answer 12

yes

Answer 13

alright do that please dont forget 2 negatives will make a positive

Answer 14

(-2*x) - (-2*4)
-2-(-8)
-10

Answer 15

you almost had it right only you would leave -2 alone and add the x and make -8 a positive
\[y-1=-2x+8\]

Answer 16

now to isolate y we have to get -1 on the other side how would we do that?

Answer 17

add -1 to both sides?

Answer 18

y = -2x + 9?

Answer 19

yes you got it :)

Answer 20

Write an equation of the line that passes through (8, 3) and (4, 3).

would this be y=3?