Those 3 numbers are solutions to the equation set equal to 0
This can be written as
[tex](x - 7)(x + 3)(x - 2)[/tex]
Multiplying out:
[tex]( {x}^{2} - 4x - 21)(x - 2) \\ {x}^{3} - 2 {x}^{2} - 4 {x}^{2} + 8x - 21x + 42 \\ {x}^{3} - 6 {x}^{2} - 13x + 42[/tex]