(x+y) (x+y) - (x-y) (x-y)​

4xy

Step-by-step explanation:

(x+y) (x+y) - (x-y) (x-y)​

(x² + xy + xy + y²) - (x² - xy - xy + y²)

(x² + 2xy + y²) - (x² - 2xy + y²)

x² + 2xy + y² - x² + 2xy - y²

x² - x² + 2xy + 2xy + y² - y²

4xy

that could literally be anything, as long as the first sum is greater then the second.

example;

(2+4) (3+5) - (6+1) (5+2)

(or, 6+8 = 14, 7+7 = 14, 14 - 14 = 0)

hope this helped :)

yes because there is exactly one y value for every x value

for function there can't be more than one value for every x value