Answer :
Factor the equation:
(x-7)(x+4)
Solve for X:
X-7=0 x+4=0
X=7 x=-4
A zero is when the function crosses the x-axis which is solved by setting the function equal to zero.
[tex]x^2-3x-28=0\\
x^2-7x+4x-28=0\\
x(x-7)+4(x-7)=0\\
(x+4)(x-7)=0\\
x=-4 \vee x=7[/tex]