Line AB goes through the points A (0, –4) and B (6, 2). Which equation represents line AB?
y – 4 = 3x
y – 2 = 3(x – 6)
y + 4 = x
y + 6 = x + 2

Question

Line AB goes through the points A (0, –4) and B (6, 2). Which equation represents line AB? 
y – 4 = 3x
y – 2 = 3(x – 6)
y + 4 = x
y + 6 = x + 2

anonymous · Answer

To find the equation of the line, first find the slope through the slope formula.
$$m=\frac{ y_2-y_1 }{ x_2-x_1 }$$
Plug in the points into the equation.
$$m=\frac{ 2+4 }{ 6-0 }$$
m = 6/6
m = 1

Plug that into the y - y_1 = m(x - x_1) formula.
y + 4 = 1(x - 0)
y + 4 = x

The third choice is correct.