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Sequences and Series — High School Algebra 2 practice questions

16 multiple-choice questions and 17 flashcards on Sequences and Series, about 11% of the High School Algebra 2 bank. Every one carries a written rationale.

Written and maintained by the CoStudy team · last updated 2026-10-12 · how we write and review questions

What this chapter covers

Sequences and Series is one of 9 chapters in CoStudy's High School Algebra 2 bank, and it holds 16 of the bank's 150 multiple-choice questions — roughly 11% of the total. That proportion is not arbitrary: chapters follow the certifying body's published exam outline, and the number of questions in each is set by that domain's published weight, so the share of your practice time this chapter takes matches the share of the real exam it accounts for.

Studying by chapter is worth doing once you have a diagnostic score. A single overall percentage tells you whether you are close; it does not tell you which domain is dragging. Working a weak chapter in isolation, and re-testing it in isolation, is the fastest way to move a score that has stalled — and it is why the mock exams in CoStudy report by domain rather than as one number.

Free Sequences and Series practice questions

1 questions drawn from this chapter, with the full rationale shown — the controlling principle behind the right answer, and why each wrong option tempts and fails.

An arithmetic sequence has a₁ = 3 and d = 4. What is a₁₅?

  1. 63
  2. 59
  3. 56
  4. 60

Answer: B — 59

B) Correct — aₙ = a₁ + (n − 1)d = 3 + 14 · 4. A) Uses n · d instead of (n − 1)d. C) Forgets to add a₁. D) Computes 15 · 4.

Sequences and Series flashcards

4 cards from the 17 in this chapter.

What's the sum of the first n terms of an arithmetic sequence?

Sₙ = n(a₁ + aₙ)/2.

Worked Example: Find the sum of the arithmetic series 3 + 7 + 11 + 15 + … + 99.

Step 1: Identify a₁, d, and the last term aₙ. a₁ = 3, common difference d = 4, last term aₙ = 99. Step 2: Use aₙ = a₁ + (n − 1)d to find n. 99 = 3 + (n − 1)·4 96 = 4(n − 1) n − 1 = 24 n = 25 Step 3: Apply the arithmetic series sum formula. Sₙ = n(a₁ + aₙ)/2 S₂₅ = 25(3 + 99)/2 Step 4: Compute. S₂₅ = 25·102/2 = 25·51 = 1275 Final answer: sum = 1275.

What's an 'arithmetic sequence'?

Each term is obtained by adding a constant (common difference) to the previous.

What's a 'geometric sequence'?

Each term obtained by multiplying the previous by a constant (common ratio).

Practise the full chapter

These are a sample. The full Sequences and Series chapter runs 33 items with per-chapter progress tracking, on the web and in the iOS app.

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