Question

What is the y coordinate of the y−intercept of the line that passes through the points
(−3, −1) and (1, 7)?
I really need help this is the last question on my assignment!

Answer 1

formula \[y-y _{1}=\frac{ y _{2}-y _{1} }{ x _{2}-x _{1} }(x-x _{1})\]is

Answer 2

here\[x _{1}=-3,y _{1}=-1,x _{2}=1,y _{2}=7\]

Answer 3

the slope of ur line is\[\frac{ y _{2}-y _{1} }{ x _{2}-x _{1} }\]

Answer 4

now try to find out the equation of line

Answer 5

Oh i get it! thanks so much !(:

Answer 6

welcome

Answer 7

but u hv to find out y intercept

Answer 8

did u find out y intercept

Answer 9

anyway wts the equation of line u got

Answer 10

First we need to find the slope ....
slope(m) = (y2 - y1)/(x2 - x1)
set 1 (-3,-1) set 2 (1,7)
now sub in your points
m = (7 - (-1)/ (1 - (-3)
m = (7 + 1)/(1 + 3)
m = 8/4 = 2
your slope is 2
now we will use this formula : y = mx + b
using slope 2 and either of your points....I will use (1,7)
y = mx + b
7 = 2(1) + b
7 = 2 + b
7 - 2 = b
5 = b

your equation in slope intercept form is y = 2x + 5
If you need it in standard form,Ax + By = C, it is :
y = 2x + 5
-2x + y = 5 (multiply by -1 to make x positive)
2x + (- y )= - 5