How do I find slope of a line from a table?

Question

If I have the table,

 

X               y

-1             -9

3              11

5              21

 

How would I find the slope?

Answer 1

You simply have three points on the line

(-1, -9), (3, 11), (5, 21)

 

Use any two of them to find the slope

 

m = (y₂-y₁)/(x₂-x₁) 

   = (11-(-9))/(3-(-1))

   = 20/4

   = 5

 

You can test using another pair if you wish:

m = (21-(-9))/(5-(-1)) = 30/6 = 5

 

m = (21-11)/(5-3)= 10/2 = 5