Question

Select the equation in standard form for the line that passes through (-9, 8) and (1, -12).

A) x + 2y = -20
B) 2x + y = -13
C) 2x+y = 7
D) 2x+y = -10
E) x + 2y = 20

Answer 1

Answer: D

Explanation:

Since we are given 2 points, we can use that to find slope, convert to slope-intercept form, and then manipulate it to be standard form. Standard form is ax+by=c.

`m=(y_2-y_1)/(x_2-x_1)=(-12-8)/(1-(-9)) =(-20)/(10) =-2`

With m=-2, we can plug it into slope-intercept form to find the y-intercept.

`y=-2x+b` [plug in point]

`8=-2(-9)+b` [multiply]

`8=18+b` [subtract both sides by 18]

`b=-10`

With m and b, we can plug in the equation.

`y=-2x-10` [add both sides by 2x]

`2x+y=-10`

This gives D as the answer.