Rút gọn các biểu thức sau

1. (x - 2)^2 - (x + 3)^2 = (x^2 - 4x + 4) - (x^2 + 6x + 9) = -10x - 5

2. (x + 8)^3 - (x - 4)(x + 4) = (x^3 + 24x^2 + 192x + 512) - (x^2 - 16) = x^3 + 24x^2 + 192x + 512 - x^2 + 16 = x^3 + 23x^2 + 192x + 528

3. (x - 3)(x + 3) - (x - 4)^2 = (x^2 - 9) - (x^2 - 8x + 16) = -8x + 7

4. (2x + 1)^2 - 4(x + 3)(x - 3) = (4x^2 + 4x + 1) - (4x^2 - 36) = 40 - 4x

5. (3x - 2)^2 - 9(x - 2)(x + 2) = (9x^2 - 12x + 4) - (9x^2 - 36) = 24x + 40

6. (x + 5)^2 - (x + 4)(x - 4) = (x^2 + 10x + 25) - (x^2 - 16) = 10x + 41

7. (x + 4)^3 - 12x(x + 4) = (x^3 + 12x^2 + 48x + 64) - (12x^2 + 48x) = x^3 + 64

8. (x - 5)^3 + 15x(x - 5) = (x^3 - 15x^2 + 75x - 125) + (15x^2 - 75x) = x^3 - 50

9. (x + y)^3 - 2xy(x + y) = (x^3 + 3x^2y + 3xy^2 + y^3) - 2xy(x + y) = x^3 + 3x^2y + 3xy^2 + y^3 - 2x^2y - 2xy^2 = x^3 + x^2y + y^3

10. (x - y)^3 + 3xy(x - y) = (x^3 - 3x^2y + 3xy^2 - y^3) + 3xy(x - y) = x^3 - 3x^2y + 3xy^2 - y^3 + 3x^2y - 3xy^2 = x^3 - y^3

11. (2x + y)(2x - y) - 4(x^2) = (4x^2 - y^2) - 4x^2 = -y^2

12. (3x + y)(3x - y) - 9 = (9x^2 - y^2) - 9 = 9x^2 - y^2 - 9

13. (x + 3y)(x - 3y) - x(x + y) = (x^2 - 9y^2) - (x^2 + xy) = -9y^2 - xy

14. (x - 3y)^2 - (x + 3y^2) = (x^2 - 6xy + 9y^2) - (x^2 + 3y^2) = -6xy + 6y^2

15. (x + y)^2 - (x - y)^2 = (x^2 + 2xy + y^2) - (x^2 - 2xy + y^2) = 4xy

16. (x - y)^2 - (x + y)^2 = (x^2 - 2xy + y^2) - (x^2 + 2xy + y^2) = -4xy

17. (x + 5y)^2 - (x - 5y)^2 = (x^2 + 10xy + 25y^2) - (x^2 - 10xy + 25y^2) = 20xy

18. (5x - y^2)(5x + y^2) = 25x^2 - y^4

19. (x + 3)(x - 3) = x^2 - 9

20. (x - 4)(x + 4) - x(x - 2)(x - 8)^2 = (x^2 - 16) - (x^3 - 10x^2 + 16x - 64) = -x^3 + 10x^2 - 16x + 48