Page 142 - IM_Algebra2_FL Print Sample.pdf

a.
b.
4. A geometric sequence has zeroth term 100 and rst term 90. a.
b.
5. Write an expression representing the 100th term of a geometric sequence that has rst term 2 and second term 8.
6. Write an expression representing the 100th term of an arithmetic sequence that has rst term 2 and second term 8.
Student Response
1. b
2. b
3. a
4. b
5. 6.
Activity Synthesis
For the rst four questions, share the correct answers with students and then invite one students to share how they reasoned about each expression.
Highlight the fact that when you start with the rst term • start with 2 and add on 9 4’s to get the 10th term
• start with 2 and multiply by 3 9 times to get the 10th term But when you start with the zeroth term
• Start with 100 and subtract 10 10’s to get the 10th term
• Start with 100 and multiply by 0.9 10 times to get the 10th term
If any students reasoned about the target expression by writing out all the values of the rst 10 terms, this approach can be shown to illustrate why you only need to add 9 4’s or multiply by 3 9 times to nd the value of the 10th term.
Unit 1 Lesson 7: Closed Form De nitions 77