To solve this set it equal to 0
[tex]0 = {x}^{2} + 43x + 120[/tex]
Now factor
[tex]0 = (x + 40)(x + 3)[/tex]
Set each side to 0 and solve
[tex]x + 40 = 0 \\ x = - 40 \\ x + 3 = 0 \\ x = - 3[/tex]
So the zeros (where it crosses the x axis) are
[tex]x = - 40 \\ x = - 3[/tex]
