The value of y when x=7

y = 49

Step-by-step explanation:

y ∝ x²

=> y = kx²

Where k is the constant of proportionality

k = 1 (We've found this out in the previous question)

Now,

y = ? when x = 7

The above equation becomes:

=> y = (1) (7) ²

=> y = (1) (49)

=> y = 49