Question

cost of lunch ($)
1 2 3 4 5 6 7 8 9 x
days since school started
which is correct about the graphs slope?
its slope is positive.
its slope is negative.
its slope is zero.
it has no slope.

Explanation:

Step1: Recall slope formula

The slope formula is $m=\frac{y_2 - y_1}{x_2 - x_1}$.

Step2: Select two points

Let's take two points on the line, say $(1, 2.5)$ and $(5, 2.5)$.

Step3: Calculate slope

$m=\frac{2.5 - 2.5}{5 - 1}=\frac{0}{4}=0$. Since for any two - points on this horizontal line, the change in the $y$ - values ($\Delta y$) is 0, the slope of the line is 0.

Answer:

Its slope is zero.