Question

What is the equation of the line that passes through the points (−2, 1) and (1, 10)?

3x − y = −7
3x − y = −5
3x − y = 5
x + 3y = −5

Answer 1

3x - y = -7

Explanation:

y = mx + b

m = deltay/deltax

m = (10 - 1)/[( 1 - (-2)]

m = 9/3 = 3

y = 3x + b

From (-2 | 1) we see that when x = -2, y = 1

Placing into the equation, in order to find b (y-intercept)

y = 3x + b

1 = 3(-2) + b

b = 7

y = 3x + 7 or 3x - y = -7