Answer:
- perfect square: 2, 5
- difference of squares: 1, 6
Explanation:
If the two factors are identical, their product will be a perfect square.
If one of the factors is the difference of terms that are summed in the other factor, the product will be the difference of squares.
(a +b)(a -b) = a² -b² . . . . . matches the 1st and 6th choices
(a +b)(a +b) = (a +b)² . . . . matches the 2nd and 5th choices