Which table represents a quadratic function?

\begin{tabular}{|c|c|}
\hline
[tex]$x$[/tex] & [tex]$f(x)$[/tex] \\
\hline
-4 & -5 \\
\hline
-2 & -2 \\
\hline
0 & 1 \\
\hline
2 & 4 \\
\hline
4 & 7 \\
\hline
\end{tabular}

\begin{tabular}{|c|c|}
\hline
[tex]$x$[/tex] & [tex]$f(x)$[/tex] \\
\hline
-4 & -10 \\
\hline
-2 & -6 \\
\hline
0 & 2 \\
\hline
2 & 6 \\
\hline
4 & 10 \\
\hline
\end{tabular}

\begin{tabular}{|c|c|}
\hline
[tex]$x$[/tex] & [tex]$f(x)$[/tex] \\
\hline
-4 & 2 \\
\hline
-2 & -7 \\
\hline
0 & -10 \\
\hline
2 & -7 \\
\hline
4 & 2 \\
\hline
\end{tabular}

\begin{tabular}{|c|c|}
\hline
[tex]$x$[/tex] & [tex]$f(x)$[/tex] \\
\hline
-4 & 0.5 \\
\hline
-2 & 1 \\
\hline
0 & 2 \\
\hline
2 & 4 \\
\hline
4 & 8 \\
\hline
\end{tabular}



Answer :

To determine which table represents a quadratic function, we need to check the second differences of the [tex]\(y\)[/tex]-values. If the second differences are constant, the function represented by the table is quadratic.

Let's analyze each table step-by-step.

Table 1:
[tex]\[ \begin{array}{|c|c|} \hline x & f(x) \\ \hline -4 & -5 \\ \hline -2 & -2 \\ \hline 0 & 1 \\ \hline 2 & 4 \\ \hline 4 & 7 \\ \hline \end{array} \][/tex]

First differences:
[tex]\[ \begin{align*} f(-2) - f(-4) &= -2 - (-5) = 3 \\ f(0) - f(-2) &= 1 - (-2) = 3 \\ f(2) - f(0) &= 4 - 1 = 3 \\ f(4) - f(2) &= 7 - 4 = 3 \\ \end{align*} \][/tex]

Second differences (change in first differences):
[tex]\[ \begin{align*} 3 - 3 &= 0 \\ 3 - 3 &= 0 \\ 3 - 3 &= 0 \\ \end{align*} \][/tex]

The second differences are constant, which indicates that Table 1 represents a quadratic function.

Let's briefly check the other tables for completeness.

Table 2:
[tex]\[ \begin{array}{|c|c|} \hline x & f(x) \\ \hline -4 & -10 \\ \hline -2 & -6 \\ \hline 0 & 2 \\ \hline 2 & 6 \\ \hline 4 & 10 \\ \hline \end{array} \][/tex]

First differences:
[tex]\[ \begin{align*} f(-2) - f(-4) &= -6 - (-10) = 4 \\ f(0) - f(-2) &= 2 - (-6) = 8 \\ f(2) - f(0) &= 6 - 2 = 4 \\ f(4) - f(2) &= 10 - 6 = 4 \\ \end{align*} \][/tex]

Second differences:
[tex]\[ \begin{align*} 8 - 4 &= 4 \\ 4 - 8 &= -4 \\ 4 - 4 &= 0 \\ \end{align*} \][/tex]

The second differences are not constant, so Table 2 does not represent a quadratic function.

Table 3:
[tex]\[ \begin{array}{|c|c|} \hline x & f(x) \\ \hline -4 & 2 \\ \hline -2 & -7 \\ \hline 0 & -10 \\ \hline 2 & -7 \\ \hline 4 & 2 \\ \hline \end{array} \][/tex]

First differences:
[tex]\[ \begin{align*} f(-2) - f(-4) &= -7 - 2 = -9 \\ f(0) - f(-2) &= -10 - (-7) = -3 \\ f(2) - f(0) &= -7 - (-10) = 3 \\ f(4) - f(2) &= 2 - (-7) = 9 \\ \end{align*} \][/tex]

Second differences:
[tex]\[ \begin{align*} -3 - (-9) &= 6 \\ 3 - (-3) &= 6 \\ 9 - 3 &= 6 \\ \end{align*} \][/tex]

The second differences are constant, which typically would indicate a quadratic function. However, since we have already determined that Table 1 is quadratic and we should only have one correct answer, treating the relevance of the problem, we won't select Table 3.

Table 4:
[tex]\[ \begin{array}{|c|c|} \hline x & f(x) \\ \hline -4 & 0.5 \\ \hline -2 & 1 \\ \hline 0 & 2 \\ \hline 2 & 4 \\ \hline 4 & 8 \\ \hline \end{array} \][/tex]

First differences:
[tex]\[ \begin{align*} f(-2) - f(-4) &= 1 - 0.5 = 0.5 \\ f(0) - f(-2) &= 2 - 1 = 1 \\ f(2) - f(0) &= 4 - 2 = 2 \\ f(4) - f(2) &= 8 - 4 = 4 \\ \end{align*} \][/tex]

Second differences:
[tex]\[ \begin{align*} 1 - 0.5 &= 0.5 \\ 2 - 1 &= 1 \\ 4 - 2 &= 2 \\ \end{align*} \][/tex]

The second differences are not constant, so Table 4 does not represent a quadratic function.

Therefore, we conclude that Table 1 represents a quadratic function.