Find the minimum (the lowest point) of the function f(x) = 3x2 + 15x − 18. Explain how you know it is the lowest. Homework Help ✎
The vertex is the lowest point of a parabola.
The x-coordinate of the vertex is halfway between the x-intercepts.
Substitute the x-coordinate of the vertex back into the equation to find the y-coordinate.
( −2.5, −36.75 )