Objective: Use slope-intercept form and standard form to graph equations. 2.4 Quick Graphs of Linear Equations

Vocabulary y-intercept: the y-coordinate of a point where a graph intersects the y-axis Where the graph crosses the y-axis Slope-intercept form: a linear equation of the form y=mx+b

Graphing Equations in Slope-Intercept Form 1. Write the equation in slope-intercept form by solving for y. 2. Find the y-intercept and plot the corresponding point. 3. Find the slope and use it to plot a second point on the line. 4. Draw a line through the two points.

Use Slope-Intercept to Graph a Line

Graph y=-2x+2

Graph

Use Slope-Intercept Form to Graph a Line Graph

Standard Form An x-intercept is the x-coordinate of a point where a graph intersects the x-axis. Every linear equation can be written in the standard form Ax + By = C where A and B are not both zero.

Graphing Equations in Standard Form 1. Write the equation in standard form. 2. Find the x-intercept by letting y=0 and solving for x. Plot the corresponding point. 3. Find the y-intercept by letting x=0 and solving for y. Plot the corresponding point. 4. Draw a line through the two points.

Graph Using Standard Form

Graph 3x+2y=12

Graph x + y = 7

Graph 5x+2y=10

Parallel and Perpendicular Lines Two lines are parallel if they lie in the same plane and never intersect. Two lines are perpendicular if they intersect to form a right angle.

Slopes of Parallel & Perpendicular Lines The lines are parallel if and only if they have the same slope. m 1 = m 2 The lines are perpendicular if and only if their slopes are negative reciprocals of each other. m 1 = 2 m 2 = −½

Homework: Complete on a separate piece of paper.