A linear function can be used to model the relationship between [tex]\( x \)[/tex] and [tex]\( y \)[/tex] shown in the table.

[tex]\[
\begin{tabular}{|c|c|c|c|c|}
\hline
$x$ & 1 & 3 & 5 & 7 \\
\hline
$y$ & -6 & 6 & 18 & 30 \\
\hline
\end{tabular}
\][/tex]

What is the equation of this linear function?

A. [tex]\( y = 3x - 11 \)[/tex]

B. [tex]\( y = 6x - 12 \)[/tex]

C. [tex]\( y = 3x + 3 \)[/tex]

D. [tex]\( y = 6x - 20 \)[/tex]



Answer :

To determine the equation of the linear function that best fits the given data points [tex]\((x, y)\)[/tex], we can follow these steps:

1. Collect the Given Data Points:
From the table, we have the following pairs of [tex]\(x\)[/tex] and [tex]\(y\)[/tex] values:
[tex]\[ \begin{array}{cccc} (1, -6) & (3, 6) & (5, 18) & (7, 30) \\ \end{array} \][/tex]

2. Calculate the Slope and Intercept:
A linear function is of the form [tex]\(y = mx + b\)[/tex], where [tex]\(m\)[/tex] is the slope and [tex]\(b\)[/tex] is the intercept.

Using linear regression techniques:
[tex]\[ m = \frac{(n \sum xy - \sum x \sum y)}{(n \sum x^2 - (\sum x)^2)} \\ b = \frac{(\sum y \sum x^2 - \sum x \sum xy)}{(n \sum x^2 - (\sum x)^2)} \][/tex]
where [tex]\(n\)[/tex] is the number of data points.

Given:
[tex]\[ \begin{align*} \sum x &= 1 + 3 + 5 + 7 = 16, \\ \sum y &= -6 + 6 + 18 + 30 = 48, \\ \sum xy &= 1(-6) + 3(6) + 5(18) + 7(30) = -6 + 18 + 90 + 210 = 312, \\ \sum x^2 &= 1^2 + 3^2 + 5^2 + 7^2 = 1 + 9 + 25 + 49 = 84. \end{align*} \][/tex]

Plugging these into the formulas:
[tex]\[ \begin{align*} m &= \frac{4 \cdot 312 - 16 \cdot 48}{4 \cdot 84 - 16^2} \\ &= \frac{1248 - 768}{336 - 256} \\ &= \frac{480}{80} \\ &= 6, \\ b &= \frac{48 \cdot 84 - 16 \cdot 312}{4 \cdot 84 - 16^2} \\ &= \frac{4032 - 4992}{336 - 256} \\ &= \frac{-960}{80} \\ &= -12. \end{align*} \][/tex]

3. Form the Linear Equation:
With the calculated slope [tex]\(m = 6\)[/tex] and intercept [tex]\(b = -12\)[/tex], the equation of the linear function is:
[tex]\[ y = 6x - 12. \][/tex]

Therefore, the correct equation that models the relationship between [tex]\(x\)[/tex] and [tex]\(y\)[/tex] as given in the table is:
[tex]\[ \boxed{y = 6x - 12} \][/tex]