Answer:
A
Step-by-step explanation:
Any rational expression where the denominator is zero is undefined.
The only expression where the denominator is zero is A 
Let

be the mean and

the standard deviation.
Joe's score tells you that

, while Jon's score says

. Solve this to get

and

.
Answer:
m=undefined; 12/0
Step-by-step explanation:
The classmate's mistake is that she should have placed the y and top and the x on the bottom.
m= 10+2/8-8
m= 12/0
The slope is undefined, meaning that it is a vertical line.
Answer:
x-9 = 9 x-9 = -9
Step-by-step explanation:
(x - 9)^2 = 81
Take the square root of both sides
sqrt((x - 9)^2) = ±sqrt(81)
x-9 = ±9
x-9 = 9 x-9 = -9