Exercise 28 Page 178

We can calculate the slope by substituting the given points into the Slope Formula.

m = \frac{y _{2} - y _{1}}{x _{2} - x _{1}}

In the above equation,

(x_{1}, y_{1})

and

(x_{2}, y_{2})

represent two points on the line. Note that it does not matter which point we use as

(x_{1}, y_{1}),

and which point we use as

(x_{2}, y_{2}) .

The result of using the Slope Formula will be the same.

m = \frac{y _{2} - y _{1}}{x _{2} - x _{1}}

Substitute $(5, - 4)$ & $(9, - 4)$

m = \frac{- 4 - ( - 4 )}{9 - 5}

▼

Add and subtract terms

$a - (- b) = a + b$

m = \frac{- 4 + 4}{9 - 5}

Add and subtract terms

m = \frac{0}{4}

Calculate quotient

m = 0

The slope of the line that passes through the given points is

0 .

It means that the line is horizontal.