Draw the following graphs:
y = 2x, y = 2x + 1, y = 2x + 2 and y = 2x + 3.
Ordered pairs for the graph y = 2x
x  2  1  0  1  2 
y = 2x  4  2  0  1  4 
Ordered pairs  (2,4)  (1,2)  (0,0)  (1,2)  (2,4) 
Ordered pairs for the graph y = 2x + 1
x  2  1  0  1  2 
y = 2x + 1  3  1  1  3  5 
Ordered pairs  (2,3)  (1,11)  (0,1)  (1,3)  (2,5) 
Ordered pairs for the graph y = 2x + 2
x  2  1  0  1  2 
y = 2x + 2  2  0  2  4  6 
Ordered pairs  (2,2)  (1,0)  (0,2)  (1,4)  (2,6) 
Ordered pairs for the graph y = 2x + 3
x  2  1  0  1  2 
y = 2x + 3  1  1  3  5  7 
Ordered pairs  (2,0)  (1,1)  (0,2)  (1,5)  (2,7) 
Observing above graphs:
1. All the lines are straight lines.
2. All the lines are parallel to each other.
3. The slopes of these lines are equal and it is 2.
If the slopes are equal, then the lines are parallel, conversely, if the lines are parallel, then the slopes are equal. 
Directions: Draw the graphs for:
y = 3x, y = 3x + 1, y = 3x + 2 and y = 3x + 3.
