Introduction to Slopes and Intercepts

Introduction to Slopes and Intercepts

OBJECTIVE: Identify the sign of the slope and intercepts given a graph.

Coordinate Plane

The coordinate plane is made of two axes.

The x-Axis is the horizontal (left to right) line.

The y-Axis is the vertical (up and down) line.

Ordered Pairs

Always written in the form (x,y)

They tell us WHERE the point is on the coordinate plane.

The x-value tells us to move left or right

The y-value tells us to move up or down

Multiple Choice

What are the coordinates of Point P?

• (-3,2)

• (2,-3)

Describing the Graph

• Where it crosses the y-axis is the y-intercept.

• Where it crosses the x-axis is the x-intercept.

• How STEEP it is is called the SLOPE.

y-intercept

• Can be stated TWO WAYS

• ONE: just the number where is crosses the y-axis. In this case -2.

• TWO: the coordinates of where it crosses. In this case (0,-2).

x-intercept

• Can be stated TWO WAYS

• ONE: just the number where is crosses the x-axis. In this case 4.

• TWO: the coordinates of where it crosses. In this case (4,0).

Multiple Choice

What is the y-intercept of the line shown?

• (0,-4)

• (-4,0)

• (0,1)

• (1,0)

Multiple Choice

What is the x-intercept of the line shown?

• (0,-4)

• (-4,0)

• (0,1)

• (1,0)

Open Ended

What do these two lines have in common?

Open Ended

What is different about these two lines?

POSITIVE SLOPE

UP from left to right

NEGATIVE SLOPE

DOWN from left to right

SLOPE OF ZERO

HORIZONTAL line

UNDEFINED SLOPE

VERTICAL line

Multiple Select

Which graph(s) have a POSITIVE slope?

Multiple Select

Which graph(s) have a NEGATIVE slope?

Multiple Select

Which graph(s) have an UNDEFINED slope?

Multiple Select

Which graph(s) have a slope of ZERO?