Derive geometric series formula

Start lessonBegins with Vocabulary and derivation · Slides

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Lesson Plan · Guided Notes · Exit Ticket · Re-teach · Homework

Lesson Plan →Objectives, pacing and practice, built from this lesson's brief.
Guided Notes →One page your students fill in and keep.
Exit Ticket →Three items at the end of class. No student accounts.
Re-teach →After an exit ticket: who missed what, and what to do tomorrow.
Homework →Assign practice; it grades itself.

HSA.SSE.B.4

**HSA.SSE.B.4**: Derive the formula for the sum of a finite geometric series (when the common ratio is not 1), and use the formula to solve problems. For example, calculate mortgage payments.

HSA.SSE.B.4: Derive the formula for the sum of a finite geometric series (when the common ratio is not 1), and use the formula to solve problems. For example, calculate mortgage payments.

What you'll learn

Identify a geometric series and state the first term, common ratio, and number of terms
Derive the formula S = a(1 - r^n)/(1 - r) using the multiply-and-subtract technique, and explain each step of the derivation
Apply the formula to compute the sum of any finite geometric series where r != 1
Handle the special case r = 1 correctly (sum = na) and explain why the main formula cannot be used when r = 1
Solve real-world problems (savings plans, loan payments, repeated geometric growth) using the geometric series formula

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