Simplify the following expressions. x²-9 16. (x - 3)² 25. 56. 6x²y 12xy² 2xy 3x 8. 2y² +6 2y +6 3x -12 6 9y2 4x-16 21y² + 3y A. 2m 14 m² - 4m - 21 - 10 m²- 9m - 22 11 m²-13m +22 n² + 3n-10 2 n' - 4n+4 旗 n²+5n+6 12-2n-15 n a²-1 a² + 2a + 1 a² + 4a +4 a²-4 3​