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Lesson 4.3. Slope Intercept Form. Graphing Lines using Slope. We can graph a line using only 2 pieces of information: The slope of the line ( m ) The y-intercept ( b ). Slope-Intercept Form. Because of this, a common way to write equations is using slope-intercept form. y= mx+b
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Lesson 4.3 Slope Intercept Form
Graphing Lines using Slope • We can graph a line using only 2 pieces of information: • The slope of the line (m) • The y-intercept (b)
Slope-Intercept Form • Because of this, a common way to write equations is using slope-intercept form. • y=mx+b • where m is the slope • and b is the y-intercept
Begin with the Basics • Ex1) Write an equation in slope-intercept form using the given information. a) Slope: 5 y-int: -3 b) Slope: y-int: 2
Begin with the Basics • Ex2) Identify the slope and y-intercept of the following equations. a) y = 2x + 4 b)
Begin with the Basics • Ex3) Write the equation for the following lines in slope-intercept form. a) b)
Re-writing equations • Ex4) Re-write the following equation in slope-intercept form. Then identify the slope and y-intercept a) 2x – y = -3 b) 3x + 5y = 15
Real World Application • Ex5) An online store charges $3 per order plus $1.00 per book for shipping. Write a linear equation in slope-intercept to model the situation. Identify the slope and y-intercept. What do they mean in the context of this problem?
Real World Application • Ex6) You want to rent a rowboat for a fishing trip. There is an initial fee of $25, plus a $50 daily fee. Write a linear equation for this situation where y represents the cost of renting a rowboat and x represents the number of days rented.
Graphing using Slope-Intercept Form • Slope-Intercept form allows us to easily graph lines. Here are the three steps: • Use the y-intercept to mark the first point • Starting at the y-intercept, use the slope to get a second point • Connect the points with a straight line (with arrows!)
Graphing using Slope-Intercept Form • Ex7) Graph the following equations. a) y = 2x – 4
Graphing using Slope-Intercept Form • Ex7) Graph the following equations. b) y =
Graphing using slope-intercept form • Ex8) Put the following into slope-intercept form, then graph the equation. a) x + y = – 3
Graphing using slope-intercept form • Ex8) Put the following into slope-intercept form, then graph the equation. b) 5x – 2y = 1