Identify the vertex of the parabola.
-f(x) = 3x2 + 18x + 26
A) (3, -1)
B) (3, 1)
C) (1, 3)
D) (-3, -1)

Question

Quizplus · Accepted Answer

The vertex of a parabola in the form $f(x) = ax^2 + bx + c$ can be found using the formula $(-b/2a, f(-b/2a))$. For $f(x) = 3x^2 + 18x + 26$, $a = 3$, $b = 18$, so $-b/2a = -18/(2*3) = -3$. Plugging $x = -3$ back into the equation gives $f(-3) = 3(-3)^2 + 18(-3) + 26 = 27 - 54 + 26 = -1$. Therefore, the vertex is $(-3, -1)$.

Identify the Vertex of the Parabola