You can name Plane P, many different ways,
Assuming you are asking this out of a textbook staring at a figure of a Parallelogram, their are probably points inside that shape and the way you would name it would be naming using any three points in the plane that are NOT on the same line in any order. <span />
slope = 
the slope is the value of f' (36)
f(x) = √x = 
f'(x) =
= 
f'(36) =
= 
This involves quite a lot of arithmetic to do manually.
The first thing you do is to make the first number in row 2 = to 0.
This is done by R2 = -3/2 R1 + R2
so the matrix becomes
( 2 1 1) ( -3 )
( 0 -13/2 3/2) (1/2 )
(5 -1 2) (-2)
Next step is to make the 5 in row 5 = 0
then the -1 must become zero
You aim for the form
( 1 0 0) (x)
(0 1 0) (y)
(0 0 1) ( z)
x , y and z will be the required solutions.
By using green to find the pink locate all the ponies