Final answer:
Equations y = 7x and y = 9x exhibit a proportional relationship between x and y as they maintain a constant ratio, characteristic of direct proportionality.
Step-by-step explanation:
To determine which equations show a proportional relationship between x and y, we can recall that a proportional relationship is one in which the ratio y/x remains constant. This is represented by equations of the form y = kx, where k is the constant of proportionality. Looking at the given equations:
a) y = 7x: This shows a direct proportionality with a constant of 7.
b) y = 9x: Also shows a direct proportionality with a constant of 9.
c) y = x2: This is a quadratic relationship and is not proportional.
d) y = 1/x: This represents an inverse relationship, which is also not proportional.
Therefore, the equations y = 7x and y = 9x show a proportional relationship.