1) $(x+3)(x+3) = x^2+3x+3x+9 = x^2+6x+9$

2) $(x+2)(x+2) = x^2+2x+2x+4 = x^2+4x+4$

3) $(x+1)(x-1) = x^2-x+x-1 = x^2-1$

5) $(x+5)(x-5) = x^2-5x+5x-25 = x^2-25$

6) $(x+3)(x-3) = x^2-3x+3x-9 = x^2-9$

7) $(x+1)(x-1) = x^2-x+x-1 = x^2-1$

8) $(2x+2)(2x-2) = 4x^2-4x+4x-4 = 4x^2-4$

9) $(x^2+5)(x^2-5) = x^4-5x^2+5x^2-25 = x^4-25$