Linear Equations Intro

Linear Equations

Graphing Linear Equations

Linear Graph

• An equation whose graph is a line is a linear equation.

• You can plot points on a coordinate plane to graph a linear equation.

• Example: y = -4x + 4.

X and Y Intercepts

• Linear equations have x and y-intercepts. 

• The x-intercept is the x-coordinate of the point at which the graph crosses the x-axis.

• The y-intercept is the y-coordinate of the point at which the graph crosses the y-axis. 

Multiple Choice

What is the x-intercept of the graph?

• (5,0)

• (0,5)

• (0,4)

• (4,0)

Multiple Choice

What is the y-intercept?

• (0,15)

• (3,0)

• (15,0)

• (0,3)

Multiple Choice

What is the y-intercept?

• (2,0)

• (0,2)

• (0,-2)

• (-2,0)

Graphing an Equation

• You need only 2 points to graph a line.

• You can choose a value for x, and then evaluate for y.

Make a Table of Values or T-Chart

• Choose a value for x, plug in, and solve for y.

• Do this 2 or 3 times.

• Then, use the points to graph your equation.

Build a t-chart

• The Red Arrow shows y=-4 after simplifying.

• The Green Arrow shows y=0 after simplifying.

• The Yellow Arrow shows y=4 after simplifying.

Graph

• Plot each ordered pair.

• Connect with a line.

• The points were (0,-4), (2,0), (4,4)

Fill in the Blank

If x = 2, in the equation y = 3x - 5, what is the value of y?

Fill in the Blank

If x = 0, in the equation y = -2x - 4, what is the value of y?

Fill in the Blank

If x = -2, in the equation y = -3x - 10, what is the value of y?

Fill in the Blank

If x = -6, in the equation y = 5x + 7, what is the value of y?

Fill in the Blank

If x = 4, in the equation x + y = -12, what is the value of y?

Fill in the Blank

If x = -3, in the equation -2x + y = 15, what is the value of y?

Fill in the Blank

If x = 4, in the equation y = -5x, what is the value of y?

Fill in the Blank

If x = 5, in the equation 5x + y = 20, what is the value of y?