A exponential function is given by:
![y=ab^x](https://img.qammunity.org/2023/formulas/mathematics/high-school/hye5rg1h8wj3ohgdt4j1vpepdhoym0w9ex.png)
y represents the output.
a represents the initial value of the function.
b represents the rate of growth.
x represents the input.
Using the given points:
![\begin{gathered} (-2,1.91) \\ 1.91=ab^(-2)_{\text{ }}(1) \\ ------- \\ (-1,2.1) \\ 2.1=ab^(-1)_{\text{ }}(2) \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/d1rjkrlhvvo9g8qkxjgxfikoojgngx5cra.png)
From (2) solve for b:
![b=(a)/(2.1)_{\text{ }}(3)](https://img.qammunity.org/2023/formulas/mathematics/college/smenyg2bwngh5g9a6yf4cfea5ktlgf73rd.png)
Replace (3) into (1):
![\begin{gathered} 1.91=(a)/(b^2) \\ 1.91b^2=a \\ 1.91((a)/(2.1))^2=a \\ (191)/(441)a^2=a \\ (191)/(441)a=1 \\ a=(441)/(191) \\ \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/r18jtgcku3gf5oaufojh5vn26tzkjlob4c.png)
Replace a into (3):
![\begin{gathered} b=(210)/(191) \\ \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/k76gp2osudxon3jbi5xydr1up034mbpu5y.png)
a.
b = 210/191
b.
![(210)/(191)-1=0.09948](https://img.qammunity.org/2023/formulas/mathematics/college/qydyiqou707gvyhqjp4dg51l5tuoxioiy7.png)
c.
![a=(441)/(191)](https://img.qammunity.org/2023/formulas/mathematics/college/67cbr1lis0h6gshv0eygjaa4j435yrtvme.png)
d.
![f(x)=(441)/(191)\cdot((210)/(191))^x](https://img.qammunity.org/2023/formulas/mathematics/college/m75n4el4dcbywow0fuarb64md8gm69q0a8.png)