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Slope and y-Intercept Form. Lesson 5-3. y=mx+b. _________. _________. An equation in the form of ______________ is in ________-_______________ form. y = mx + b. slope. intercept. y - intercept. slope. y = 4 x – 5. y = 4 x + 6. -3. y = 2x – 3. 3. y = – 2x + 3.
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Slope and y-Intercept Form Lesson 5-3
y=mx+b _________ _________ An equation in the form of ______________ is in ________-_______________ form. y = mx + b slope intercept y - intercept slope y = 4x – 5 y = 4x + 6
-3 y = 2x – 3
3 y = – 2x + 3
II. Write an equation in slope-intercept form for each graph.
-7 (0, -7) up 1 right 2
Graph (0, -4). Find additional points by going up 2 and right 1.
Graph (0, 5). Find additional points by going up 3 and left 4 OR down 3 and right 4.
5x – 5x + 4y = 8 – 5x 4y = 8 – 5x
3x – 3x + 2y = 6 – 3x 2y = 6 – 3x 3
V. Write an Equation in Slope-Intercept Form • Suppose you have already saved $50 toward • the cost of a new television set. You plan to • save $5 more each week for the next several weeks. • What is your starting point? _______ • (This will be your _______________.) • What action is being repeated? _____________________ • (This becomes the ____________________.) • Write the equation ________________________ $50 y - intercept Saving $5 each week slope y = 5x + 50
Practice: Write an equation in slope-intercept for each situation. 14. A video store charges $15 for a rental card plus $1.50 per rental. A Norfolk pine is 22 inches tall and grows at a rate of 1.4 feet per year. (Careful, all units must be the same!) 16. A terrier weighs 32 pounds and is on a special diet to lost 3 pounds per month. An airplane at an altitude of 2000 feet ascends at a rate of 750 feet per mile.
WRITING AN EQUATION GIVEN TWO POINTS. (You must write these on your own paper.) Directions: Write an equation in slope-intercept form that passes through the line containing the two points given. M. (-2, 4) and (3, -1) Step 1: Find the slope. Step 2: Find the y-intercept (b) Substitute a point in the equation and solve for “b” y = mx + b 4= (-1)(-2) + b 4= 2+ b 4 - 2= 2 - 2+ b 2= b y = mx + b y = -1x + 2 y = -x +2 Step 3: Write the equation substituting the value of m and b
N. (-2, -1) and (4, 2) Step 1: Find the slope. Step 2: Find the y-intercept (b) Substitute a point in the equation and solve for “b” y = mx + b 2= (1/2)(4) + b 2= 2+ b 2 - 2= 2 - 2+ b 0= b y = mx + b y = ½ x + 0 y= ½ x Step 3: Write the equation substituting the value of m and b
O. (-6, 5) and (1, 0) Step 1: Find the slope. Step 2: Find the y-intercept (b) Substitute a point in the equation and solve for “b” y = mx + b 0= (-5/7)(1) + b 0= -5/7+ b 0 + 5/7= -5/7 + 5/7 + b 5/7= b y = mx + b y = -5/7x + 5/7 Step 3: Write the equation substituting the value of m and b
P. (2, -6.9) and (-4, 4.6) Step 1: Find the slope. Step 2: Find the y-intercept (b) Substitute a point in the equation and solve for “b” y = mx + b 6.9= (1.15)(-2) + b 6.9= -2.3+ b 6.9 + 2.3= -2.3 + 2.3 + b 9.2= b y = mx + b y = 1.15x + 9.2 Step 3: Write the equation substituting the value of m and b
Watch these videos to help you understand slope-intercept form. Virtual Nerd on Slope-Intercept Form Homework Tutor - Graphing a Line Using Slope Intercept Form Homework Tutor - Writing Equations in Slope-Intercept form Homework Tutor - Equations from Graphs