Circle : A circle is a two-dimensional shape. The boundary of a circle is a set of points that has the same distance (the radius) from the center of the circle.

Constant : Constant is another word for a fixed number that is mainly used in the context of expressions or functions like $f(x)=c$ that are equal to the same number irrespective of any variable.

Function : A function is a mapping in which every element in one set is mapped to exactly one element of a second set. Most often the mapping is described using a rule. For example the function $f(x)=x+1$ maps 2 to 3 and -1 to 0.

Graph : The graph of a function is the set of points $\{(x,f(x))\}$ that can be blotted in a coordinate system.

Horizontal : In the direction from left to right.

Line : A line AB is a one-dimensional shape that includes the points A and B, all the points on the line segment in between A and B and all the points of the straight extension of the line segment beyond A and B. A line does not have an endpoint.

Map : In mathematics mapping means assigning exactly one value to an object. A function maps every $x$ to exactly one $y.$

Vertical : In the direction from down to up.

Function : A function is a mapping in which every element in one set is mapped to exactly one element of a second set. Most often the mapping is described using a rule. For example the function $f(x)=x+1$ maps 2 to 3 and -1 to 0.

Graph : The graph of a function is the set of points $\{(x,f(x))\}$ that can be blotted in a coordinate system.

Function : A function is a mapping in which every element in one set is mapped to exactly one element of a second set. Most often the mapping is described using a rule. For example the function $f(x)=x+1$ maps 2 to 3 and -1 to 0.

Monotonically decreasing : A function $f$ is called monotonically decreasing if we have $f(x)\geq f(y)$ for every $x\lt y.$ For example the function $f(x)=-x$ is monotonically decreasing and so is the function $f(x)=e^{-x}.$ A differentiable function $f$ is monotonically decreasing if and only if $f^{\prime}\leq 0.$

Monotonically increasing : A function $f$ is called monotonically increasing if we have $f(x)\leq f(y)$ for every $x\lt y.$ For example the function $f(x)=x$ is monotonically increasing and so is the function $f(x)=x^3.$ A differentiable function $f$ is monotonically increasing if and only if $f^{\prime}\geq 0.$

Negative : A number is negative if it is $\lt 0.$

Positive : Positive means $\geq 0.$