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\begin{tabular}{|c|c|}
\hline
[tex]$x$[/tex] & [tex]$f(x)$[/tex] \\
\hline
-2 & 0.2 \\
\hline
-1 & 0.4 \\
\hline
0 & 0.8 \\
\hline
1 & 1.6 \\
\hline
2 & 3.2 \\
\hline
\end{tabular}

Which exponential function is represented by the table?

A. [tex]$f(x) = 2(2^x)$[/tex]
B. [tex]$f(x) = 0.8(0.8^x)$[/tex]
C. [tex]$f(x) = 2(0.8^x)$[/tex]
D. [tex]$f(x) = 0.8(2^x)$[/tex]


Sagot :

To determine which of the given exponential functions matches the table of values, we will evaluate each function at the specified [tex]\(x\)[/tex] values and compare the results to the given [tex]\(f(x)\)[/tex] values.

The functions to consider are:

1. [tex]\(f(x)=2\left(2^x\right)\)[/tex]
2. [tex]\(f(x)=0.8\left(0.8^x\right)\)[/tex]
3. [tex]\(f(x)=2\left(0.8^x\right)\)[/tex]
4. [tex]\(f(x)=0.8\left(2^x\right)\)[/tex]

Let's evaluate each function at the given [tex]\(x\)[/tex] values: [tex]\(-2, -1, 0, 1, 2\)[/tex].

### Evaluating [tex]\(f(x)=2\left(2^x\right)\)[/tex]
[tex]\[ \begin{aligned} f(-2) &= 2(2^{-2}) = 2 \left(\frac{1}{4}\right) = 0.5, \\ f(-1) &= 2(2^{-1}) = 2 \left(\frac{1}{2}\right) = 1, \\ f(0) &= 2(2^0) = 2(1) = 2, \\ f(1) &= 2(2^1) = 2(2) = 4, \\ f(2) &= 2(2^2) = 2(4) = 8. \end{aligned} \][/tex]

### Evaluating [tex]\(f(x)=0.8\left(0.8^x\right)\)[/tex]
[tex]\[ \begin{aligned} f(-2) &= 0.8 (0.8^{-2}) = 0.8 \left(\frac{1}{(0.8)^2}\right) = 0.8 \left(\frac{1}{0.64}\right) \approx 1.25, \\ f(-1) &= 0.8 (0.8^{-1}) = 0.8 \left(\frac{1}{0.8}\right) = 1, \\ f(0) &= 0.8 (0.8^0) = 0.8, \\ f(1) &= 0.8 (0.8^1) = 0.8 \cdot 0.8 = 0.64, \\ f(2) &= 0.8 (0.8^2) = 0.8 \cdot 0.64 = 0.512. \end{aligned} \][/tex]

### Evaluating [tex]\(f(x)=2\left(0.8^x\right)\)[/tex]
[tex]\[ \begin{aligned} f(-2) &= 2 (0.8^{-2}) = 2 \left(\frac{1}{(0.8)^2}\right) = 2 \left(\frac{1}{0.64}\right) \approx 3.125, \\ f(-1) &= 2 (0.8^{-1}) = 2 \left(\frac{1}{0.8}\right) = 2.5, \\ f(0) &= 2 (0.8^0) = 2, \\ f(1) &= 2 (0.8^1) = 2 \cdot 0.8 = 1.6, \\ f(2) &= 2 (0.8^2) = 2 \cdot 0.64 = 1.28. \end{aligned} \][/tex]

### Evaluating [tex]\(f(x)=0.8\left(2^x\right)\)[/tex]
[tex]\[ \begin{aligned} f(-2) &= 0.8 (2^{-2}) = 0.8 \left(\frac{1}{4}\right) = 0.2, \\ f(-1) &= 0.8 (2^{-1}) = 0.8 \left(\frac{1}{2}\right) = 0.4, \\ f(0) &= 0.8 (2^0) = 0.8, \\ f(1) &= 0.8 (2^1) = 0.8 \cdot 2 = 1.6, \\ f(2) &= 0.8 (2^2) = 0.8 \cdot 4 = 3.2. \end{aligned} \][/tex]

### Conclusion
Comparing the results of each function evaluation to the given values [tex]\(f(x)\)[/tex]:

[tex]\[ \begin{array}{cc} x & f(x) \\ -2 & 0.2 \\ -1 & 0.4 \\ 0 & 0.8 \\ 1 & 1.6 \\ 2 & 3.2 \\ \end{array} \][/tex]

We observe that the evaluations of [tex]\(f(x) = 0.8(2^x)\)[/tex]:

[tex]\[ \begin{aligned} f(-2) &= 0.2, \\ f(-1) &= 0.4, \\ f(0) &= 0.8, \\ f(1) &= 1.6, \\ f(2) &= 3.2, \end{aligned} \][/tex]

Exactly match the table values. Hence, the exponential function represented by the table is:

[tex]\[ \boxed{f(x) = 0.8\left(2^x\right)} \][/tex]