Functions
Determine whether the relation is a function:
(1,4)
(2,7)
(3,9)
(1,8)
Not a function. Input 1 has two outputs.
A scatterplot shows points moving upward from left to right. What type of correlation is present?
Positive
Solve:
2x+5=17
x = 6
A movie ticket costs $12.
Write an expression for the cost of x tickets.
12x
Student simplifies:
3(x+4)
Student answer:
3x + 4
What mistake did they make?
Failed to distribute correctly.
A function has the rule:
f(x) = 3x - 2
Find f(5).
f(5) = 13
A survey shows:
60 students
36 play sports
What percent of students play sports?
60%
Find the slope between:
(2,3)
(6,11)
A gym charges:
$20 membership fee
$10 per month
Write an equation.
y = 10x + 20
Find the value of:
-32
Student answer:
9
What was the mistake that the student made?
They assumed you had to square (-3). Rather you were asked to square (3) and then multiply by -1.
Which graph represents a growth function?
Exponential curve
A two-way table shows:
Passed Failed
Tutoring 24 6
No Tutoring 15 15
Which group had a higher pass rate?
Tutoring
The line has slope 3 and passes through (2,5).
Find an equation.
y = 3x - 1
A bacteria culture triples every hour.
Starting amount: 50
Write a function rule to model this situation.
y = 50(3)^x
Solve:
x2−16=0
Student answer:
x = 4
What mistake was made?
Forgot the second solution.
x = ±4
A function passes through:
(1,4)
(2,8)
(3,16)
(4,32)
Linear or exponential? How do you know?
Exponential. There is a growth factor of 2.
Which regression model would best fit:
Population doubles every year.
BE SPECIFIC
Exponential Growth
Solve the system:
x + y = 10
x − y = 4
(7,3)
A car loses 15% of its value each year.
Starting value:
$20,000
What is the value of the car after one year?
$17,000
A car loses 15% each year.
A student believes the decay factor is 0.15.
Identify the mistake
1 - 0.15 = 0.85