Answer:
0 ≤ t ≤ 5.
Step-by-step explanation:
In the function
,
is the independent variable. The domain of
is the set of all values of
that this function can accept.
In this case,
is defined in a real-life context. Hence, consider the real-life constraints on the two variables. Both time and volume should be non-negative. In other words,
.
.
The first condition is an inequality about
, which is indeed the independent variable.
However, the second condition is about
, the dependent variable of this function. It has to be rewritten as a condition about
.
.
Hence, t ≤ 5.
Combine the two inequalities to obtain the domain:
0 ≤ t ≤ 5.
Substitute the numbers in the equation:

Since L=5in, W=4in and H=8in:

Therefore, the volume is equal to 160 inches cubed.
|-1/5| < |-1/3| < |-7|
Your answer:
B. y = -1/5 x^2; y = -1/3 x^2; y = -7x^2
Look at the picture.