Question

Line CD contains points A (4, −7) and B (4, 8). The slope of line CD is

Answer 1

Answer:

Undefined

Step-by-step explanation:

Slope=m=y2-y1/x2-x1=8- (-7)/4-4=8+7/4-4=15/0 so you can't divide by zero and calculator will give you an error. Thus, the answer is undefined. This means there is no horizontal change, which is another way to say the line is vertical. All vertical lins have a slope that is "undefined".

Answer 2

Given two points; A(x₁,y₁) and B(x₂,y₂) the slope "m" is:
m=(y₂-y₂)/(x₂-x₁)   or   m=(y₁-y₂)/(x₁-x₂)

In this case:
A(4,-7)
B(4,8)

m=(-7-8) / (4-4)=-15/0  because we have "0" in the denominator the line is vertical, and its slope is indefinitely.