### Home > AC > Chapter 12 > Lesson 12.4.4 > Problem12-101

12-101.

Find the minimum (the lowest point) of the function $f(x) = 3x^2 + 15x − 18$. Explain how you know it is the lowest.

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.

$( −2.5, −36.75 )$