The product of (a - b)(a -b) is a perfect square trinomail. sometimes, always or never?

Ineed with number 17 i don’t get it at alll

Consider the table below. x y -1 -5 0 5 1 11 2 13 3 11 complete the standard form equation representing the quadratic relationship displayed above, where a, b, and c are constants.

What’s the domain of this function? fastttt