At 1P.M. (4 hours after 9A.M.), the temperature is 75 degrees Fahrenheit.
B
b
At m hours after 9A.M., the temperature is 70 degrees.
C
c
The temperature at 11A.M. (2 hours after 9A.M.) is the same as the temperature at 6P.M. (9 hours after 9A.M.).
D
d
The temperature at 3P.M. (6 hours after 9A.M.) is greater than the temperature at 9 .A.M.
Practice makes perfect
a
Function notation is one way to write functions. It explicitly shows that y is a function of x.
f(x)=y
In the given situation we have f(t)=y, where t is the number of hours after 9A.M. and y is the temperature at that time. We will use this to explain the meaning of the given statement.
f(4)=75
Comparing this to f(t)=y, we can see that t=4 and y=75. Therefore, the statement is telling us that 4 hours after 9A.M. — at 1P.M. — the temperature is 75 degrees Fahrenheit.
b
Let's look at the given statement.
f(m)=70
Comparing this to f(t)=y, we can see that t=m and y=70. Therefore, the statement is telling us that at m hours after 9A.M. the temperature is 70 degrees Fahrenheit.
c
Let's look at the given statement.
f(2)=f(9)
Comparing this to f(t)=y, we can see that the temperature at t=2 is equal to the temperature at t=9. Therefore, the statement is telling us that the temperature at 11A.M. (2 hours after 9A.M.) is the same as the temperature at 6 .P.M (9 hours after 9A.M.).
d
Let's look at the given statement.
f(6)>f(0)
Comparing this to f(t)=y, we can see that the temperature at t=6 is greater than the temperature at t=0. Therefore, the statement is telling us that the temperature at 3P.M. (6 hours after 9A.M.) is greater than the temperature at 9A.M..
