Today we did two word problems on sequences and started preparing for writing the scribe posts.
The first problem (1st slide) was about an arithmetic sequence. It seemed many people got caught up in trying find and use "the correct formula." A better approach was to think about it logically. The key question to ask was, "How many jumps?". Some people thought that there were 15 jumps, others thought 16. Drawing a small part of a number line was a great way to decide that 16 was correct.
Remember, a recursive definition has two parts:
- Define the 1st term
- Define the rule for producing the next term from the one(s) before it.
Reminders:
- Scribe posts start Thursday and Lala and Diego volunteered to go first. Don't forget to read the post about writing scribe posts so you know what is expected.
- Quiz on Wednesday
The second problem was a geometric sequence. Again, there was confusion about whether the number was 8 or 9 jumps. Either would work but it depended on what you chose for the first term.
One way to think about it is that the laptop lost value 8 times so there should be 8 terms in our sequence. In this case, the first term would be 75% of the purchase price or $1500. On the other hand, if you use the purchase price as the first term, then you need 8 more terms for each year of loss. In that case, you have 9 terms.
Either way, the geometric sequence formula, tn = t1*r^(n-1), works.
STUDY! STUDY! STUDY!
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