Question

This is confusing. help plz

Answer 1

$a=-1$, because the parabola has the maximum, not the minimum, (∩)

The Vertex form of a parabola equation:
V(-3;4), so:
$f(x)=a(x-p)^2+q$
$f(x)=-1(x+3)^2+4$

*   $f(x)=-(x+3)^2+4$

The zeros and the conix form of a parabola equation:
$x_1=-5$
$x_2=-1$
$f(x)=a(x-x_1)(x-x_2)$, so:

*   $f(x)=-(x+5)(x+1)$

We can also use the general form of a parabola:
$f(x)=ax^2+bx+c$ 

$f(x)=-(x+5)(x+1)=-(x^2+x+5x+5)=-x^2-x-5x-5=-x^2-6x-5$

*   $f(x)=-x^2-6x-5$

The answers: A, C, E

:)