College

Convert the equation [tex]f(t) = 122(0.89)^t[/tex] to the form [tex]f(t) = a e^{kt}[/tex].

- [tex]a = 122[/tex]
- [tex]k = \square[/tex]

Answer :

To convert the equation [tex]\( f(t) = 122(0.89)^t \)[/tex] to the form [tex]\( f(t) = a e^{k t} \)[/tex], we can follow these steps:

1. Identify the base of the exponential: In the given equation, the base of the exponent is 0.89.

2. Express the base in terms of the natural exponential function: We can use the property that any positive number can be expressed with base [tex]\( e \)[/tex] (the natural exponential number, approximately 2.718). To do this, we use natural logarithms:

[tex]\[
0.89 = e^{\ln(0.89)}
\][/tex]

Therefore, [tex]\( (0.89)^t = \left(e^{\ln(0.89)}\right)^t \)[/tex].

3. Apply the power rule of exponents: Using the property [tex]\((e^x)^y = e^{xy}\)[/tex], we get:

[tex]\[
(0.89)^t = e^{t \cdot \ln(0.89)}
\][/tex]

4. Substitute back into the equation: Replace [tex]\( (0.89)^t \)[/tex] with [tex]\( e^{t \cdot \ln(0.89)} \)[/tex] in the original equation:

[tex]\[
f(t) = 122 \times e^{t \cdot \ln(0.89)}
\][/tex]

Now, the equation is in the desired form [tex]\( f(t) = a e^{k t} \)[/tex], where:

- The coefficient [tex]\( a \)[/tex] is 122.
- The exponent's coefficient [tex]\( k \)[/tex] is the value of [tex]\( \ln(0.89) \)[/tex].

The calculated value of [tex]\( k \)[/tex] is approximately [tex]\(-0.11653381625595151\)[/tex].

So, in the form [tex]\( f(t) = a e^{k t} \)[/tex], we have:

- [tex]\( a = 122 \)[/tex]
- [tex]\( k \approx -0.11653381625595151 \)[/tex]

This completes the conversion of the equation to the requested form.