f(x)= -2x^2+4x+6
We can use -b/2a to find the line of symmetry
a= -2
b= 4
c= 6
and the x value for the line of symmetry gives you the x value for the vertex
-4/(2*-2)
-1=x
Plug this x value back into the function to find the y value for the vertex
f(x)= -2(-1)^2+(4*-1)+6
f(x)= -2+(-4)+6
f(x)= 0
the c value is the y intercept
Vertex: (-1,0)
Y intercept: 6