Question

What is the equation of the line, in slope-intercept form, that contains the points (-1,8) and (2,-1)?

A) y= -3x +5
B) y= -x+5
C) y= x+5
D) y= -x+3

Answer 1

y-yo = m (x-xo)
We must find the slope of the line:
m = (y2-y1) / (x2-x1)
m = (- 1-8) / (2 - (- 1))
m = (- 9) / (3)
m = -3
The ordered pair is:
(xo, yo) = (- 1, 8)
Substituting:
y-8 = -3 (x + 1)
Rewriting:
y = -3x-3 + 8
y = -3x + 5

Answer:
The equation of the line is:
A) y = -3x +5

Answer 2

Correct Answer: Option A

From the given points, we can find the slope(m):


`m= (-1-8)/(2-(-1)) =-3`

Thus the slope of the line containing the given two pints is -3.

Using slope, and a point we can write the equation as:

y - 8 = -3 ( x + 1)
y - 8 = -3x -3
y = -3x + 5