Answer:
rise from left to right
Step-by-step explanation:
Linear equation: 
(where  is the slope and
 is the slope and  is the y-intercept)
 is the y-intercept)
<u>Positive slope</u>: rise from left to right
 is a positive number
 is a positive number

<u>Negative slope</u>: fall from left to right
 is a negative number
 is a negative number

<u>Zero slope</u>: horizontal line


Therefore, a horizontal line is  (where
 (where  is some constant)
 is some constant)
<u>Infinite slope</u>: vertical line


There is no change in x-values for a vertical line, so:

We also usually call the slope of this line undefined.
Therefore, a vertical line is  (where
 (where  is some constant)
 is some constant)
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<u>Attached graph</u>:
Positive slope: black line
Negative slope: blue line
Zero slope: green line
Infinite slope: red line