Chapter 3.4, Problem 25PPS

To determine

To write an equation of line through $(-1,-4)$ and $(3,-4)$ in slope intercept form.

Answer to Problem 25PPS

Slope intercept form

  $y=-4$

Explanation of Solution

Given information:

Line through $(-1,-4)$ and $(3,-4)$

Formula used:

Slope, $m=\frac{y_2-y_1}{x_2-x_1}$

Point-slope form

  $y-y_1=m(x-x_1)$

Slope intercept form

  $y=mx+b$

Calculation:

Points

$(-1,-4)$ and $(3,-4)$

Here

  $x_1=-1$

  $y_1=-4$

  $x_2=3$

  $y_2=-4$

Using slope formula to calculate slope of line

  $m=\frac{-4-(-4)}{3-(-1)}$

On solving

  $m=\frac{0}{4}$

On solving

  $m=0$

Using slope and any one of the point to find slope intercept form

  $m=\frac{9}{7}$

Let take point $(-1,-4)$

Here

  $x_1=-1$

  $y_1=-4$

Point-slope form

  $y-(-4)=0(x-(-1))$

On solving

  $y+4=0$

Subtract 4 both sides

  $y+4-4=0-4$

On solving

  $y=-4$

Hence, slope intercept form is $y=-4$