Ответ:

[tex]6 {a}^{4} + 9 {a}^{3} b = 3 {a}^{3} (2a + 3b) \\ 18 {m}^{2} - 2 {n}^{2} = 2(9{m}^{2} - {n}^{2}) = 2(3 m - n)(3 m + n )[/tex]