Draw the graph of y = 2x + 1, y = 2x and y = 2x - . Are these parallel?

Given y = 2x + 1
If x = 0
⇒ y = 2(0) + 1 = 1
If x = 1
⇒ y = 2(1) + 1 = 2 + 1 = 3
If x = -2
⇒ y = 2(-2) + 1 = - 4 + 1 = - 3

x	0	1	-2
y	1	3	-3

Given y = 2x
If x = 0
⇒ y = 0
If x = 1
⇒ y = 2(1) = 2
If x = -2
⇒ y = 2(-2) = -4 

x	0	1	-2
y	0	2	-4

Given y = 2x -   
If x = 0
⇒ y = 2x -   = -  
If x = 1
⇒ y = 2x –  = 2  –  = 3/2
If x =  – 2
⇒ y = 2x  –  =  – 4 –   =  – 9/2   

x	0	1	-2
y	-0.5	1.5	-4.5

 y = 2x + 1, y = 2x and y = 2x – are parallel to each other.