Answer:
[tex]3(x + 9) \times (x + 8)[/tex]
Step-by-step explanation:
[tex] {3x}^{2} + 51x + 216[/tex]
[tex]3( {x}^{2} + 17x + 72)[/tex]
[tex]3( {x}^{2} + 9x + 8x + 72)[/tex]
[tex]3(x \times (x + 9) + 8(x + 9))[/tex]
[tex] = 3(x + 9) \times (x + 8)[/tex]
