(x - 5)^2 =
(x - 5)(x - 5) =
x^2 - 5x - 5x + 25 =
x^2 - 10x + 25 <===
first is proportional. y is 1 and 1/4 times x
second is not proportional.
reason? divided any y value by its corresponding x value and you'll keep getting 1.25, or 1 and 1/4. and the second one is not proportional because dividing the y values by their corresponding x value will give different answers.
maybe im wrong maybe im right you choose to trust me or not.