College

Sort the sequences according to whether they are arithmetic, geometric, or neither.

1. [tex]\( 98.3, 94.1, 89.9, 85.7, \ldots \)[/tex]
2. [tex]\( 1, 0, -1, 0, \ldots \)[/tex]
3. [tex]\( 1.75, 3.5, 7, 14 \)[/tex]
4. [tex]\( -12, -10.8, -9.6, -8.4 \)[/tex]
5. [tex]\( -1, 1, -1, 1, \ldots \)[/tex]

- **Arithmetic:**
- Sequence 1: [tex]\( 98.3, 94.1, 89.9, 85.7, \ldots \)[/tex]
- Sequence 4: [tex]\( -12, -10.8, -9.6, -8.4 \)[/tex]

- **Geometric:**
- Sequence 3: [tex]\( 1.75, 3.5, 7, 14 \)[/tex]

- **Neither:**
- Sequence 2: [tex]\( 1, 0, -1, 0, \ldots \)[/tex]
- Sequence 5: [tex]\( -1, 1, -1, 1, \ldots \)[/tex]

Answer :

Let's analyze the sequences one by one to determine if they are arithmetic, geometric, or neither:

1. Sequence 1: [tex]\(98.3, 94.1, 89.9, 85.7, \ldots\)[/tex]

- Arithmetic Sequences have a constant difference between consecutive terms.
- Here, [tex]\(94.1 - 98.3 = -4.2\)[/tex], [tex]\(89.9 - 94.1 = -4.2\)[/tex], [tex]\(85.7 - 89.9 = -4.2\)[/tex].
- Since the difference is constant, this sequence is Arithmetic.

2. Sequence 2: [tex]\(1, 0, -1, 0, \ldots\)[/tex]

- This sequence fluctuates between 1, 0, -1, and back to 0.
- Arithmetic Sequences have constant differences, and Geometric Sequences have constant ratios.
- The fluctuation means neither a constant difference nor a constant ratio is present.
- This sequence is Neither.

3. Sequence 3: [tex]\(1.75, 3.5, 7, 14\)[/tex]

- Geometric Sequences have a constant ratio between consecutive terms.
- Here, [tex]\(3.5 / 1.75 = 2\)[/tex], [tex]\(7 / 3.5 = 2\)[/tex], [tex]\(14 / 7 = 2\)[/tex].
- Since the ratio is constant, this sequence is Geometric.

4. Sequence 4: [tex]\(-12, -10.8, -9.6, -8.4\)[/tex]

- Check for an Arithmetic Sequence by looking for a constant difference.
- Here, [tex]\(-10.8 - (-12) = 1.2\)[/tex], [tex]\(-9.6 - (-10.8) = 1.2\)[/tex], [tex]\(-8.4 - (-9.6) = 1.2\)[/tex].
- Since the difference is constant, this sequence is Arithmetic.

5. Sequence 5: [tex]\(-1, 1, -1, 1, \ldots\)[/tex]

- Similar to Sequence 2, this pattern switches between -1 and 1.
- There is no consistent pattern for an Arithmetic Sequence (constant difference) or Geometric Sequence (constant ratio).
- This sequence is Neither.

In summary:
- Sequence 1 is Arithmetic.
- Sequence 2 is Neither.
- Sequence 3 is Geometric.
- Sequence 4 is Arithmetic.
- Sequence 5 is Neither.