Question

If the points (4, 7) and (4, 11) are on a given line, find the slope of this line

A) slope is zero
B) slope is 4
C) slope is 1/4
D) slope is undefined

Answer 1

The slope is undefined

Step-by step:

To obtain the slope from a line, with two points, the general equation is:

m = (y1 -y2) / (x1 -y2)

If you substitute the values in the equation you can see you will need to divide by zero, and any number divided by zero is undefined. Therefore you cannot do the operation, and you got an undefined slope. In the attached graph you will see that the values of any change in x (Δx) always will be equal to zero, because x is a constant, x = 4, for any value of y.

x1 = 4, y1 = 7

x2 = 4, y2 = 11

substitute in the previous equation:

`m = (7-11)/(4-4)`

`m = (-4)/(0)`