Answer:
- (5x + 3)(5x - 3)
- (7x + 4)(7x + 4)
- (x - 9)(x - 9)
- (-3x-6)(-3x+6)
Step-by-step explanation:
Expressions of the form (a +b)(a +b) will result in a perfect square trinomial, because both binomial factors are identical.
Expressions of the form (a +b)(a -b) will result in a difference of squares.
Match the offered choices to either one of these forms, and they will be included in the answer set.
 (5x + 3)(5x - 3) -- difference of squares
 (7x + 4)(7x + 4) -- perfect square
 (2x + 1)(x + 2) -- nothing special
 (4x-6)(x + 8) -- nothing special
 (x - 9)(x - 9) -- perfect square
 (-3x-6)(-3x+6) -- difference of squares
