Warm Up

1. The distance from a number to 0 on the number line

is the ___________________________.

Lesson 20, Graphing on a Coordinate PlaneEXPRESSIONS AND EQUATIONS, FUNCTIONS

Vocabulary

Coordinate plane: two perpendicular axes; one horizontal, one vertical

X-axis: the horizontal axis Y-axis: the vertical axis Origin: intersection of the x-axis and y-axis Ordered pair: identifies a point on the coordinate plane X-coordinate: indicates horizontal distance Y-coordinate: indicates vertical distance

Coordinate Plane

The coordinate plane has four quadrants.

The first quadrant contains all positive values

The second quadrant contains negative x values and positive y values

The third quadrant contains all negative values

The fourth quadrant contains positive x values and negative y values

Example

Graph the point Graph the point

Variables

Independent variable: the variable whose value can be chosen

Dependent variable: the variable whose value is determined by the value of another variable

Example

For each pair of variables, identify the independent variable and dependent variable.

a. Number of traffic violations, cost of auto insurance

b. Electric bill total, kilowatts of electricity used

Equations and ordered pairs

A solution to an equation with two variables is an ordered pair that makes the equation true.

The equation has infinitely many solutions.

We can find solutions by substituting values for to find the corresponding values.

Example

The federal minimum wage is about $5 per hour. The total on a minimum-wage worker’s paycheck is dependent on the number of hours worked. The paycheck total can be calculated using the equation .

Find the pay for 1, 3, 5, and 8 hours of work. Graph the solution.

Correcting homework

Be kind

Write “C.B. _____________” with your name

Hold questions until the end

Make sure I get your score sheet so your

assignment is not marked missing!

Homework

1st and 2nd hour: Lesson 20 #1-30

3rd hour: Lesson 19 #16-30

Test tomorrow! Don’t forget to study!