Question

5) Find the equation of the line passing through the points (-1,7) and (2,-8). Write the equation in slope-intercept form. Oy= 5x – 18 Oy = 5x + 12 Oy = -5.1 + 2 Oy = -5x + 7 Submit

Answer 1

We need to find the equation of the line passing through the points ( -1 , 7) and ( 2 , -8 )

The general equation of the line is :

$y=m\cdot x+b$

Where m is the slope and b is a constant represents y - intercept

The slope m will be calculated as following:

Slope = Rise/Run

Rise = -8 - 7 = -15

Run = 2 - (-1) = 2 + 1 = 3

So, the slope is:

$m=\frac{-15}{3}=-5$

The equation of the line will be :

$y=-5x+b$

b will be calculated using the point ( 2 , -8 ) as following:

when x = 2 , y = -8

So,

$\begin{gathered} -8=-5\cdot2+b \\ -8=-10+b \\ b=-8+10=2 \end{gathered}$

So, the equation of the line will be:

$y=-5x+2$

So, the answer is option C. y = -5x + 2