Parabola Vocab words, Key features of a parabola

parabola

The U-shaped graph of a quadratic function

x = -b/2a

An "x = ..." equation is how to write the line of symmetry and it should match the x-coordinate of the vertex.

maximum point

If the parabola is facing downward then the y-value of the vertex is the highest point of the graph.

minimum point

If the parabola is facing upward then the y-value of the vertex is the lowest point of the graph.

vertex

The maximum (highest point) or minimum (lowest point) on the graph.

Decreasing Interval

The part of the parabola that goes down from left to right

Increasing interval

The part of the parabola that goes up from left to right

Domain

The x values. For a parabola, this is always All Real Numbers

Range

The y values. For a parabola, this will start or end at the y value of the vertex.

opens down

a<0, vertex is a maximum point

opens up

a>1, vertex is a minimum point

direction (positive smile or negative frown)

open up or open down

line/ axis of symmetry

the "fold line" of the parabola. The invisible line that cuts the parabola in half vertically. The vertex is on this line. Drawn in with a dashed line.

y-intercept

the point where the parabola crosses or touches the y-axis

x - intercept(s)

the point(s) where the parabola crosses or touches the x - axis

root or zero

the solution to the equation or where the graph crosses the x-axis.

(0, y)

this is how to write the coordinate point of a y-intercept

(x, 0)

this is how to write the coordinate point of an x-intercept.