Questions: A tank is being filled with a liquid. L(t), given below, is the amount of liquid in liters in the tank after t minutes.
L(t)=1.25 t+61
Complete the following statements.
Let L^(-1) be the inverse function of L
Take x to be an output of the function L.
That is, x=L(t) and t=L^(-1)(x).
(a) Which statement best describes L^(-1)(x) ?
The ratio of the amount of liquid (in liters) to the number of minutes, x.
The reciprocal of the amount of liquid (in liters) after x minutes.
The amount of time (in minutes) it takes to have x liters of liquid.
The amount of liquid (in liters) after x minutes.
(b) L^(-1)(x)=0
(c) L^(-1)(115)=
Transcript text: A tank is being filled with a liquid. $L(t)$, given below, is the amount of liquid in liters in the tank after $t$ minutes.
\[
L(t)=1.25 t+61
\]
Complete the following statements.
Let $L^{-1}$ be the inverse function of $L$
Take $x$ to be an output of the function $L$.
That is, $x=L(t)$ and $t=L^{-1}(x)$.
(a) Which statement best describes $L^{-1}(x)$ ?
The ratio of the amount of liquid (in liters) to the number of minutes, $x$.
The reciprocal of the amount of liquid (in liters) after $x$ minutes.
The amount of time (in minutes) it takes to have $x$ liters of liquid.
The amount of liquid (in liters) after $x$ minutes.
(b) $L^{-1}(x)=0$
(c) $L^{-1}(115)=\square$
Solution
Solution Steps
Step 1: Determine the inverse function \( L^{-1}(x) \)
The function \( L(t) = 1.25t + 61 \) describes the amount of liquid in the tank after \( t \) minutes. To find the inverse function \( L^{-1}(x) \), we solve for \( t \) in terms of \( x \):
\[
x = 1.25t + 61
\]
Subtract 61 from both sides:
\[
x - 61 = 1.25t
\]
Divide both sides by 1.25:
\[
t = \frac{x - 61}{1.25}
\]
Thus, the inverse function is:
\[
L^{-1}(x) = \frac{x - 61}{1.25}
\]
Step 2: Answer part (a)
The inverse function \( L^{-1}(x) \) represents the amount of time (in minutes) it takes to have \( x \) liters of liquid in the tank. Therefore, the correct statement is:
The amount of time (in minutes) it takes to have \( x \) liters of liquid.
Step 3: Answer part (b)
We are asked to find \( L^{-1}(x) = 0 \). Using the inverse function:
\[
L^{-1}(x) = \frac{x - 61}{1.25} = 0
\]
Solve for \( x \):
\[
\frac{x - 61}{1.25} = 0 \implies x - 61 = 0 \implies x = 61
\]
Thus, \( L^{-1}(x) = 0 \) when \( x = 61 \).
Step 4: Answer part (c)
We are asked to find \( L^{-1}(115) \). Using the inverse function:
\[
L^{-1}(115) = \frac{115 - 61}{1.25} = \frac{54}{1.25} = 43.2
\]
Thus, \( L^{-1}(115) = 43.2 \).
Final Answer
(a) The amount of time (in minutes) it takes to have \( x \) liters of liquid.
(b) \( \boxed{x = 61} \)
(c) \( \boxed{L^{-1}(115) = 43.2} \)