Transcript Warm-Up 1.6

Algebra 3
Lesson 1.6
Objective:
SSBAT write equations that model real life data.
Standards: M11.A.2.2.1, M11.D.2.1.3 and
M11.D.3.2.3
Warm-Up 1.6
Write an equation for each given the slope & y-intercept.
1. m = 3 and b = -4
2. m = ¾ and b = 8
3. m = - ½ and b = 20
4. m = -7 and b = 15.5
Writing a Linear Equation for a Real Life Application
 Slope (m) = Rate of Change
 Y-intercept (b) = Initial Value, Starting Amount,
Original Amount, Base Pay, etc.
1. You buy a house for $125,000 and it is expected to
increase in value at the rate of $4,000 per year. Write
an equation describing the value of the house (y) in
terms of the number of years (x).
Beginning value = $125,000
Rate of change = $4,000 per year.
b  125,000
m  4,000
Using slope - intercept form
y  4,000 x  125,000
2. You buy an automobile for $23,000 and it is
expected to depreciate in value at the rate of
$2,400 per year. Write an equation describing the
value of the car (y) in terms of the number of
years (x).
Beginning value = $23,000
Rate of change = – $2,400 per year.
b  23,000
m  2,400
Using slope - intercept form :
y  2,400 x  23,000
3. Joe is paid $800 a month plus 15% of his sales.
a) Write an equation to represent Joe’s
earnings, y, for x dollars of sales.
b) Find Joe’s earnings (y) if he has $10,000 in
sales for a month
a)
Base Pay = 800
Rate = 15%  .15
y = .15x + 800
3. Joe is paid $800 a month plus 15% of his sales.
a) Write an equation to represent Joe’s
earnings, y, for x dollars of sales.
b) Find Joe’s earnings (y) if he has $10,000 in
sales for a month
b)
Let x = 10000 and solve for y
y = .15(10000) + 800
y = $2300
 He would make $2300 for that month if he had $10000 in sales.
4. You can rent a car from Company A for $49 a day plus
$0.10 a mile.
a) Write an equation to represent the total cost, y,
to rent a car for x number of miles.
b) Find the cost to rent a car for a day if you are to
travel 65 miles that day.
a) m = 0.10
and b = 49
y = 0.10x + 49
b) Let x = 65
y = 0.10(65) + 49
y = $55.50
5.
A plane starts its descent at 34,500 feet. It will descend at a
constant rate, which is 1500 feet per minute.
a) Write an equation to show the planes altitude, y,
after descending x number of minutes.
b) Find the height of the plane after 12 minutes
c) Find how long it will take the plane to land
a) m = -1500 and b= 34500
y = -1500x + 34500
b) Let x = 12 
y = -1500(12) + 34500
y = 16500 feet
c) Let y = 0 
0 = -1500x + 34500
1500x = 34500
x = 23 minutes
Complete Worksheet 1.6