115k views
1 vote
Write down the formula for the nth number and calculate the 10th number and the 101th number of the following sequence: 74, 58, 42, ...

User Fstephany
by
4.8k points

2 Answers

4 votes

Final answer:

The formula for the nth number in the given sequence is a_n = a_n-1 - 16. The 10th number in the sequence is -70 and the 101st number is -166.

Step-by-step explanation:

The given sequence is 74, 58, 42, ...

To find the formula for the nth number, we need to look for a pattern in the sequence. By subtracting 16 from each number, we get the sequence: 58, 42, 26, ...

Now, we can see that each number in the new sequence is obtained by subtracting 16 from the previous number. So, the formula for the nth number is: an = an-1 - 16.

Using this formula, we can calculate the 10th number as follows:

  1. a1 = 74 (given)
  2. a2 = a1 - 16 = 58
  3. a3 = a2 - 16 = 42
  4. a4 = a3 - 16 = 26
  5. a5 = a4 - 16 = 10
  6. a6 = a5 - 16 = -6
  7. a7 = a6 - 16 = -22
  8. a8 = a7 - 16 = -38
  9. a9 = a8 - 16 = -54
  10. a10 = a9 - 16 = -70

So, the 10th number in the sequence is -70.

Similarly, we can calculate the 101st number by continuing the pattern:

  1. a10 = -70 (calculated)
  2. a11 = a10 - 16 = -86
  3. a12 = a11 - 16 = -102
  4. a13 = a12 - 16 = -118
  5. ...
  6. a100 = a99 - 16
  7. a101 = a100 - 16

Calculating each step, we find that the 101st number in the sequence is -166.

User Andrew Alcock
by
5.9k points
5 votes

Answer:

nth number: 74+(n-1)*(-16)

Step-by-step explanation:

User Artur Vartanyan
by
5.3k points