Respuesta :

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.

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