t o w n & c i t y
h e l l o
The absolute value of a number
is its distance from 0.
2 is 2 away from zero, and −2 is also 2 away from zero.
The coordinate plane is a two-dimension surface formed by two number lines.
One number line is horizontal and is called the x-axis. The other number line is vertical number line and is called the y-axis.
The two axes
meet at a point
called the origin
A curve that turns in the downward direction is called a downward curve. It is also known as a concave downward.