Question

Select the equations for the lines on the graph.

Answer 1

second option

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 =
`(y_(2)-y_(1) )/(x_(2)-x_(1) )`

Red line

using (x₁, y₁ ) = (0, 0) and (x₂, y₂ ) = (2, 8) ← 2 points on the line

m =
`(8-0)/(2-0)` =
`(8)/(2)` = 4 , then

y = 4x + c ← is the partial equation

to find c substitute either of the 2 points into the partial equation

using (0, 0 ) then

0 = 4(0) + c

0 = 0 + c

0 = c

y = 4x + 0 , that is y = 4x ← equation of red line

Black line

using (x₁, y₁ ) = (0, 10) and (x₂, y₂ ) = (2, 8) ← 2 points on the line

m =
`(8-10)/(2-0)` =
`(-2)/(2)` = - 1

the line crosses the y- axis at (0, 10 ) ⇒ c = 10

y = - x + 10 ← equation of black line