Question

What is the equation of the following line? Be sure to scroll down first to see

all answer options.
(0,0) (3,9)

Answer 1

B

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, 0) and (x₂, y₂ ) = (3, - 9) ← 2 points on the line

m =
`(-9-0)/(3-0)` =
`(-9)/(3)` = - 3

Since the line passes through the origin then c = 0

y = - 3x + 0, which is simply

y = - 3x → B

Answer 2

y=-3x

Explanation:

we know that the equation of the line is:

y=mx+b

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

we have two points giver from the graph:

point 1: (0,0)

point 2: (3,-9)

we to find the slope:

m=(-9-0)/(3-0)

m=-3/3

m=-3

we need to find "b"

using the point (0,0)

we have

0=0x+b

so we have b=0

finally we have

y=-3x+0

y =-3x