whats the rule for my table?
-4 6
4 4
8 3
12 2
and what is an equation for the rule?
whats the rule for my table?
-4 6
4 4
8 3
12 2
and what is an equation for the rule?
$$\small\text{
\begin{array}{c|c|c}
\hline
n & a_n & \small{\text{difference (d)}} \\
\hline
1 & 16 & \\
& & -4\\
2 & 12 \\
& & -4\\
3 & 8 \\
& & -4\\
4 & 4 \\
& & -4\\
5 & 0 \\
& & -4\\
6 & -4 \\
\hline
\end{array}
}}$$
$$\boxed{ a_n = a_1 + (n-1)*d } \small{\text{ arithmetic series }}$$
$$a_1 = 16 \small{\text{ and }} d = -4\qquad a_n = 16 + (n-1)*(-4) \\
a_n = 16 - 4n + 4\\
a_n = 20 - 4n \\
\small{\text{The equation for }} a_n \small{\text{ is }}
\textcolor[rgb]{1,0,0}{a_n = 20 - 4n } \\ \\
n? \qquad a_n = 20 - 4n \\
4n = 20 - a_n \quad | \quad : 4 \\
n = 5 - \frac{1}{4}a_n \\
\small{\text{The equation for }} n \small{\text{ is }}\textcolor[rgb]{1,0,0}{5 - \frac{1}{4}a_n }$$
The formula for slope is: m = (y2 - y1) / (x2 - x1)
The slope from (-4, 6) to (4, 4) is: m = (4 - 6) / (4 - -4) = -2/8 = -1/4
The slope from (4, 4) to (8, 3) is: m = (3 - 4) / (8 - 4) = -1/4
The slope from (8, 3) to (12, 2) is: m = (2 - 3) / (12 - 8) = -1/4
Since the slope is always the same, these points fall on a straight line.
The point-slope formula for a straight line is: y - y1 = m(x - x1)
Using (x1, y1) = (-4, 6) and m = -1/4: y - 6 = (-1/4)(x - -4)
y - 6 = (-1/4)(x + 4)
y - 6 = (-1/4)x - 1
y = (-1/4)x + 5
Melody, you are correct, so I'll modify my answer.
If geno3141 is correct, wouldn't it simplify further to y = (-1/4)x + 11?
First let me test the rule:
$${\mathtt{\,-\,}}{\mathtt{0.25}}{\mathtt{\,\times\,}}\left(-{\mathtt{4}}\right){\mathtt{\,\small\textbf+\,}}{\mathtt{5}} = {\mathtt{6}}$$
$${\mathtt{\,-\,}}{\mathtt{0.25}}{\mathtt{\,\times\,}}\left({\mathtt{4}}\right){\mathtt{\,\small\textbf+\,}}{\mathtt{5}} = {\mathtt{4}}$$
$${\mathtt{\,-\,}}{\mathtt{0.25}}{\mathtt{\,\times\,}}\left({\mathtt{8}}\right){\mathtt{\,\small\textbf+\,}}{\mathtt{5}} = {\mathtt{3}}$$
$${\mathtt{\,-\,}}{\mathtt{0.25}}{\mathtt{\,\times\,}}\left(-{\mathtt{4}}\right){\mathtt{\,\small\textbf+\,}}{\mathtt{5}} = {\mathtt{6}}$$
It looks like Melody is accurate.
whats the rule for my table?
-4 6
4 4
8 3
12 2
and what is an equation for the rule?
$$\small\text{
\begin{array}{c|c|c}
\hline
n & a_n & \small{\text{difference (d)}} \\
\hline
1 & 16 & \\
& & -4\\
2 & 12 \\
& & -4\\
3 & 8 \\
& & -4\\
4 & 4 \\
& & -4\\
5 & 0 \\
& & -4\\
6 & -4 \\
\hline
\end{array}
}}$$
$$\boxed{ a_n = a_1 + (n-1)*d } \small{\text{ arithmetic series }}$$
$$a_1 = 16 \small{\text{ and }} d = -4\qquad a_n = 16 + (n-1)*(-4) \\
a_n = 16 - 4n + 4\\
a_n = 20 - 4n \\
\small{\text{The equation for }} a_n \small{\text{ is }}
\textcolor[rgb]{1,0,0}{a_n = 20 - 4n } \\ \\
n? \qquad a_n = 20 - 4n \\
4n = 20 - a_n \quad | \quad : 4 \\
n = 5 - \frac{1}{4}a_n \\
\small{\text{The equation for }} n \small{\text{ is }}\textcolor[rgb]{1,0,0}{5 - \frac{1}{4}a_n }$$