Question

tell whether the slope of the line is positive, negative, zero, or undefined.
a. negative
b. positive
c. undefined
d. zero

Explanation:

Step1: Recall slope formula

The slope formula is $m=\frac{y_2 - y_1}{x_2 - x_1}$, where $(x_1,y_1)$ and $(x_2,y_2)$ are two points on the line.

Step2: Analyze vertical line

For a vertical line, all points have the same $x$ - value. Let two points on the vertical line be $(x_1,y_1)$ and $(x_1,y_2)$ with $y_1
eq y_2$. Then $m=\frac{y_2 - y_1}{x_1 - x_1}=\frac{y_2 - y_1}{0}$, which is undefined.

Answer:

C. undefined