Question

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

Answer 1

Undefined

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".