3 4 Graphing Horizontal and Vertical Lines Objective

3: 4 Graphing Horizontal and Vertical Lines Objective- To graph horizontal and vertical lines. x y -2 7 -1 6 0 5 1 4 2 3 3 2 4 1 5 0 6 -1 Graph x + y = 5 y Line is oblique x 1 Algebra I by James Wenk © 2003 published by TEACHINGpoint as part of the Expert Systems for Teachers Series

x y -2 -1 0 1 2 3 4 5 3 3 3 3 Graph. y=3 Line is Horizontal y x Any line in the form y = k will be horizontal. 2 Algebra I by James Wenk © 2003 published by TEACHINGpoint as part of the Expert Systems for Teachers Series

x y -2 -2 -2 -1 0 1 2 3 4 5 Graph. x = -2 Line is Vertical y x Any line in the form x = k will be vertical. 3 Algebra I by James Wenk © 2003 published by TEACHINGpoint as part of the Expert Systems for Teachers Series

Types of Lines Oblique Horizontal Vertical Equation Ax + By = C form y=k Example y = -7 3 x - 2 y = 5 x=k A=3 k = -7 B = -2 C=5 A, B and C are integers (no fractions or decimals). k represents a rational number. Universal constants 4 Algebra I by James Wenk © 2003 published by TEACHINGpoint as part of the Expert Systems for Teachers Series

Review Horizontal Line Vertical Line y=k x=k Perpendicular to y-axis. Perpendicular to x-axis. 5 Algebra I by James Wenk © 2003 published by TEACHINGpoint as part of the Expert Systems for Teachers Series

A) Graph x = -4 on a number line. -5 -4 -3 -2 -1 0 1 2 3 B) Graph x = -4 on a coordinate plane. y x 6 Algebra I by James Wenk © 2003 published by TEACHINGpoint as part of the Expert Systems for Teachers Series

Finding Intercepts x-intercept = where the line crosses the x-axis y-intercept = where the line crosses the y-axis Horizontal y = 2 x-int. = none y-int. = 2 y Vertical x = -1 x-int. = -1 y-int. = none y x x 7 Algebra I by James Wenk © 2003 published by TEACHINGpoint as part of the Expert Systems for Teachers Series

Finding Intercepts x-intercept = where the line crosses the x-axis y-intercept = where the line crosses the y-axis Oblique y = 2 x + 3 x y -3 -3 -2 -1 -1 1 0 3 1 5 2 7 y x x-intercept (set y = 0) y = 2 x + 3 0 = 2 x + 3 -3 -3 -3 = 2 x 2 2 y-intercept (set x = 0) y = 2 x + 3 y = 2(0) + 3 y=3 8 Algebra I by James Wenk © 2003 published by TEACHINGpoint as part of the Expert Systems for Teachers Series

Find the x-intercept and y-intercept. 1) x = 5 x-intercept x = 5 or (5, 0) 2) none 3) x = -1 (-1, 0) y-intercept none 9 Algebra I by James Wenk © 2003 published by TEACHINGpoint as part of the Expert Systems for Teachers Series

Find the x-intercept and y-intercept. x-intercept (Set y = 0) 4) 4 x + 2 y = 6 4 x + 2(0) = 6 4 x = 6 4 4 y-intercept (Set x = 0) 4 x + 2 y = 6 4(0) + 2 y = 6 2 2 10 Algebra I by James Wenk © 2003 published by TEACHINGpoint as part of the Expert Systems for Teachers Series

Find the x-intercept and y-intercept. 5) 3 x - y = -5 x-intercept (Set y = 0) 3 x - y = -5 3 x - (0) = -5 3 x = -5 3 3 y-intercept (Set x = 0) 3 x - y = -5 3(0) - y = -5 -1(-y = -5) 11 Algebra I by James Wenk © 2003 published by TEACHINGpoint as part of the Expert Systems for Teachers Series