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Recall the Slope Formula. How can the terms in the sequence represent points on a line?
Slope for Sequence a: m_a=3
Slope for Sequence b: m_b=6
Slope for Sequence c: m_c=-5
Slope for Sequence d: m_d=1.5
We are asked to find the slope of the line we would get if we graphed the sequences shown below and connected the points.
&a. 5, 8, 11, 14, ... &&b. 3, 9, 15, ...
&c. 26, 21, 16, ... &&d. 7, 8.5, 10, ...
If the sequences represent linear relations, then we can find the value of the associated line's slope by using any two terms of the sequence. Let's recall the Slope Formula.
Substitute ( 1,5) & ( 2,8)
Subtract terms
Calculate quotient
The slope for the line associated with Sequence A is m=3. Notice that if we use any two consecutive terms the denominator in the Slope Formula will always be one. Therefore, the value for the slope is just the common difference of the sequence, obtained as any term minus its previous term. We can use this to find the slope for the rest of sequences.
| Sequence | Common difference | Slope |
|---|---|---|
| a. 5, 8, 11, 14, ... | 8-5 = 3 | m_a=3 |
| b. 3, 9, 15, ... | 9-3 = 6 | m_b=6 |
| c. 26, 21, 16, ... | 21-26 = -5 | m_c=-5 |
| d. 7, 8.5, 10, ... | 8.5-7 = 1.5 | m_d=1.5 |