Question

What is the axis of symmetry and y- intercept for the equation y = 3x² + 6x - 7 ?

Answer 1

Axis of symmetry is
x
=
1
, vertex is at
(
1
,
15
)
.
Explanation:
f
(
x
)
=
−
3
x
2
+
6
x
+
12
=
−
3
(
x
2
−
2
x
)
+
12
=
−
3
(
x
2
−
2
x
+
1
)
+
3
+
12
=
−
3
(
x
−
1
)
2
+
15
. Comparing with standard vertex form of equation
f
(
x
)
=
a
(
x
−
h
)
2
+
k
;
(
h
,
k
)
being vertex.
Here
h
=
1
,
k
=
15
. So vertex is at
(
1
,
15
)
.
Axis of symmetry is
x
=
1

graph{-3x^2+6x+12 [-40, 40, -20, 20]} [Ans]