Find an equation for the line passing through the points (-3,1) and (9,7)

Answer 1

find the slope using the ratio

m=(y_1-y_2)/(x_1-x_2)

if (x_1,y_1)=(9,7) and (x_2,y_2)=(-3,1) then,

m=(7-1)/(9-(-3))=6/12=1/2

plug this into y=mx+b

y=1/2x+b

use one of the points to solve for b

7=1/2(9)+b

7=9/2+b

5/2=b

then the equation is y=1/2x+5/2

Answer 2

Use two-point form:

(y - 1) / (x + 3) = (1 - 7) / (-3 -9)

Answer 3

Slope-Intercept Form:

Slope = Rise/run = (1-7)/(-3-9) = (-6)/(-12) = 0.5

Use the slope above and one of the points to calculate the intercept

Y = mx + b

1 = (0.5)(-3) + b

b = 1 + 1.5 = 2.5

Final Equation: y = 0.5x + 2.5

In standard form: -x + 2y = 5

Double check:

1 = 0.5*(-3) + 2.5

7 = 0.5*(9) + 2.5