A proportional relationship has the form: y=mx
The first three options (y=(1/3)x, y=2x, and y=3.4x) have this form. The fourth option is:
y+1=2x
If we isolate y:
y+1-1=2x-1
y=2x-1, it does not have the form y=mx
Answer: The equation that does not represent a proportional relationship is: Fourth option: y+1=2x