Marginal costs. Keep in mind that marginal means on the edge of something, so the cost of producing one more unit would be on the edge. Hope this explanation helps.
Answer:
We can also find the vertex by using the expressions:
(
−
b
2
a
,
f
(
−
b
2
a
)
)
Standard form:
a
x
2
+
b
x
+
c
=
0
In this example,
a
=
−
1
and
b
=
0
x
=
−
0
2
(
−
1
)
=
0
2
=
0
y
=
f
(
0
)
=
7
−
0
2
=
7
Same result of
(
0
,
7
)
I am not a 100% sure, but I think it would be the speaker of the house. Hope this helps
