Question

What is the equation of a line that passes through points (0, 4) and (-4, -8)?

y = 3 x - 4
y = 2 x - 4
y = 3 x + 4
y = 2 x + 4

Answer 1

Answer: C. y = 3 x + 4

Explanation:

Construct the line equation y=mx+b where m =3 and b=4

y = 3 x + 4

Answer 2

y = 3x + 4

Explanation:

The equation of a line in slope- intercept form is

y = mx + c ( m is the slope and c the y- intercept )

Calculate m using the slope formula

m = (y₂ - y₁ ) / (x₂ - x₁ )

with (x₁, y₁ ) = (0, 4) and (x₂, y₂ ) = (- 4, - 8)

m =
`(-8-4)/(-4-0)` =
`(-12)/(-4)` = 3

Note the line passes through the y- axis at (0, 4) ⇒ c = 4

y = 3x + 4 ← equation of line