Step-by-step explanation:
[tex]\tt{}( {9x}^{2} - 18x - 7)[/tex]
[tex]\tt{} {9x}^{2} + 21 - 3x - 7[/tex]
[tex]\tt{}3x \times (3x + 7) -( 3x + 7)[/tex]
[tex]\tt{}(3x + 7) \times( 3x - 1)[/tex]
[tex]9x² - 18x - 7[/tex]
[tex] {9x}^{2} - 21x + 3x - 7[/tex]
[tex]3x(x - 7) + 3(x - 7)[/tex]
[tex](3x + 3)(x - 7)[/tex]
