Question

What is the equation of the line through (2, -4) and (0, 4)?

Answer 1

Answer: C

m = slope

m = (y2 - y1) / (x2 - x1)

2 points:
(2, -4) x1 = 2 and y1 = -4
(0, 4) x2 = 0 and y2 = 4

m = (4 - (-4)) / (0- 2)

m = 8 / -2

m = -4

Equation of the line is : y = mx + b

So we got...

y = -4x + b

Then we can use any of the two points given to solve for b. I’m going to use (0, 4).

y = -4x + b

4 = -4(0) + b

4 = 0 + b

4 = b

Therefore the equation of the line is
y = -4x + 4