Students will learn how to find the formula for an arithmetic sequence given two of its terms. Using the two terms, we can setup a system of two equations in two unknowns. Solving gives us the common difference. Then plugging in the common difference, and one of the known terms, we can find the value of the first term.
Next, give your students these challenges:
- Carrying Cards by NRICH
- In the Money by NRICH
- 2020 Math Kangaroo Levels 9-10 Problem #22 by STEM4all
- 2006 AMC 8, Problem 23
- 2001 AMC 8, Problem 19
Conclude by leading this investigation:
Pinocchio’s Playmates (pattern puzzle)
by MathPickle