Answer:
-56
Step-by-step explanation:
Formula to get determinant is::
![\left[\begin{array}{ccc}a&b\\c&d\end{array}\right] = ad-bc](https://tex.z-dn.net/?f=%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7Da%26b%5C%5Cc%26d%5Cend%7Barray%7D%5Cright%5D%20%3D%20ad-bc)
0(0)-8(7)
0 - 56
-56
Ok, so user says that it should be solve for vertex not vertex form
(x,y)
to find the vertex of
y=ax^2+bx+c
the x value of the vertex is -b/2a
the y value is found by plugging in the x value for the vertex back into the original equation and evaluating
y=-2x^2-12x-28
a=-2
b=-12
xvalue of vertex is -(-12)/(2*-2)=12/-4=-3
x value of vertex is -3
plug backin for x
y=-2x^2-12x-28
y=-2(-3)^2-12(-3)-28
y=-2(9)+36-28
y=-18+8
y=-10
yvalue is -10
x value is -3
vertex is (-3,-10)
Based on the picture, PC = PD
