In general, a quadratic equation can be written in terms of its solutions:
[tex]y=(x-a)(x-b).[/tex]Now, notice that:
[tex]x+\frac{1}{2}=0\text{ }[/tex]when x= -1/2, and it is equivalent to:
[tex]2x+1=0.[/tex]Therefore, you can write the quadratic equation as:
[tex]y=(2x+1)(x-4).[/tex]Computing the above multiplication, you get:
[tex]y=2x^2-8x+x-4.[/tex]Simplifying the above equation you get:
[tex]y=2x^2-7x-4.[/tex]