# Chapter 9 Vocab

### Kritima Lamichhane

## A parabola is a curve where any point is at an equal distance from: a fixed point (the focus), and a fixed straight line (the directrix)

## The name Quadratic comes from "quad" meaning square, because the variable gets squared (like x2). It is also called an "Equation of Degree 2" (because of the "2" on the x)

## The common endpoint of two or more rays or line segments

## A line of symmetry for a graph. The two sides of a graph on either side of the axis of symmetry look like mirror images of each other.

## The height of the function at "a" is greater than (or equal to) the height anywhere else in that interval.

## Likewise, a local minimum is: f(a) ≤ f(x) for all x in the interval

## A Term is either a single number or a variable, or numbers and variables multiplied together.

## When the x-differences are all constant, then the y-differences (or first differences) are useful in telling if a set of data is nearly linear or not.

## Since these values, the "second differences", are all the same value, then I can stop. It isn't important what the second difference is (in this case, "2"); what is important is that the second differences are the same, because this tells me that the polynomial for this sequence of values is a quadratic.

## a "zero" of a function is an input value that produces an output of zero (0). A root of a polynomial is a zero of the associated polynomial function.