Answer:
To find the equation which contains both the y-intercept and slope, we use the point-slope formula.
y - y1 = m(x - x1)
But first, we must find the slope itself to find the rest of the equation for point-slope formula.
Select two random points (-3,9) and (-1,7) then use the formula;
y2 - y1
______ (to find the slope)
x2 - x1
Replace values:
7 - 9 -2
_____ = ______ = -1, the slope is -1.
-1 - (-3) 2
Now we plug this into our point-slope formula;
y - y1 = m(x - x1)
y1 = first y-coordinate (for any pair)
x1 = first x-coordinate (using the pair that used y1)
m = slope
For this, i'll be using the pair (-3,9), it does not matter which pair you use.
y - 9 = -1(x - (-3))
Distribute;
y - 9 = -1x - 3
Get rid of constants to fulfill the equation in the formula;
+9 +9
y = -1x + 6, where again, -1 is the slope and 6 is the y-intercept.
