Answer:
Complete the square to convert to vertex form.
Explanation:
y =
3
x
2
+ 12x - 15
y = 3(
x
2
+ 4x + n - n) - 15
n =
(
b
2
)
2
n = 4
y = 3(
x
2
+ 4x + 4 - 4) - 15
y = 3(
x
2
+ 4x + 4) - 12 - 15
y = 3(
x
2
+ 4x + 4) - 27
y = 3
(
x
+
2
)
2
- 27
In the form y = a
(
x
−
p
)
2
+ q, the vertex can be found at (p, q). So, the vertex is (-2, -27).
Hopefully my explanation helps!