Answer:
It has no slope because (x2-x1) in the formula
is equal to zero, and the denominator of a fraction cannot be zero
Explanation:
we know that
The formula to calculate the slope between two points is equal to
![m=(y2-y1)/(x2-x1)](https://img.qammunity.org/2021/formulas/mathematics/high-school/s22vchztbo0z3zfbr5dy5rbx0ndd5ffwx5.png)
we have
the points (7, 10) and (7, 20)
substitute the values
![m=(20-10)/(7-7)](https://img.qammunity.org/2021/formulas/mathematics/middle-school/oawdg620xlkv2cc9c8or2mlhhcfgcarfuo.png)
----> is undefined
The line has a slope undefined ---> is a vertical line (parallel to the y-axis)