5.1 Writing Linear Equations in Slope-Intercept Form

Goals:Use the slope and y-intercept to write the equation of a line.Model a real-life situation with a linear equation.

Eligible Content:A1.1.2.1.1 / A1.1.2.1.3 / A1.2.1.1.1 / A1.2.1.2.1 / A1.2.1.2.2 / A1.2.2.1.3 / A1.2.2.1.44-1 Writing Linear Equations in Slope-Intercept FormExampleWrite the equation of the line whose slope is -2 and whose y-intercept is 5.

y = mx + b y = x +

y = -2x + 5-25mbExamplesWrite an equation in slope-intercept form.Slope is 3, y-intercept is -5 y = 3x 5

m = -3, b = 6y = -3x + 6

Slope is , y-intercept is -4y = - x 4

A.y = 3x + 4B.y = 4x + 3C.y = 4xD.y = 4Write an equation in slope-intercept form of the line whose slope is 4 and whose y-intercept is 3.Write the equation of each graph.

1. 2.

Example #3Which of the following is an equation in slope-intercept form for the line shown in the graph?

A.B.C.D.

Which of the following is an equation in slope-intercept form for the line shown in the graph?

A.B.C.D.

PracticeWrite an equation in slope-intercept form.m = 5, b = 8Slope is 6, y-intercept is 3b = 4, m = y-intercept is 2, slope is -6m = 1, b = 0y = 5x + 8y = 6x 3y = x + 4y = -6x + 2y = x Word ProblemsSlope is rate of change!!!Look for words like per, for each, for every

y-intercept is the beginning amountLook for words like beginning, initial Word Problem #1Your family decides to rent bikes while you are on vacation. It costs $4 to rent the bike, plus $1.50 per hour.Write an equation in slope-intercept form that models this situation.y = 1.5x + 4

How much will it cost to rent the bike for 12 hours?$22Word Problem #2In 1990, the population in California was 29.76 million. During the next 25 years, the population increased by .31 million people per year.Write an equation in slope-intercept form that models this situation.y = .31x + 29.76

How many people were there in California in 2005?34.41 million people

Word Problem #3A telephone call costs $3.44 for the first minute, and $.24 for each additional minute.Write an equation in slope-intercept form that models this situation.y = .24x + 3.44

How much will it cost for a 9 minute phone call?$5.36

A.D = 0.15nB.D = 0.15n + 3C.D = 3nD.D = 3n + 0.15The amount of money spent on Christmas gifts has increased by an average of $150,000 ($0.15 million) per year since 1986. Consumers spent $3 million in 1986. Write a linear equation to find the average amount D spent for any year n since 1986.

A.$5 millionB.$3 millionC.$4.95 millionD.$3.5 millionThe amount of money spent on Christmas gifts has increased by an average of $150,000 ($0.15 million) per year since 1986. Consumers spent $3 million in 1986. Find the amount spent by consumers in 1999.HomeworkPages 220-221 #11-22 #37, 50,51You do not have to graph any equations!