What is the equation in point-slope form of the line passing through (1, 9) and (−1, 11)?

y + 9 = −(x − 1)
y − 9 = 1(x + 1)
y + 9 = 1(x + 1)
y − 9 = −(x − 1)

Point slope form: 


m=slope 
(x1,y1) 

First we need to find the slope using the slope formula:


Given the two coordinates: 
(1, 9) and (−1, 11)

Plug them into the slope formula: 

Simplify: 


Now we know that: 
m=-1  and the (x1,y1) would be (1, 9)

Now we simply plug in the info: 


Final y − 9 = −(x − 1)