Finite series — A/L Combined Mathematics

How do I practise Finite series?

1 question with a worked solution

Check before you answer: Sigma Linearity Application: Splitting composite summation expressions into scalar multiples of standard known sums without algebraic errors.

1. In an Arithmetic Progression (AP), the first term is a = 3 and the common difference is d = 4. What is the sum of the first 20 terms (S₂₀)?
   1. A) 1640
   2. B) 790
   3. C) 850
   4. D) 820
   Check my answer

   Correct answer: D) 820

   Using the sum formula S_n = (n / 2) [2a + (n - 1)d] with n = 20, a = 3, d = 4: S₂₀ = (20 / 2) [2(3) + (19)(4)] = 10 [6 + 76] = 10 × 82 = 820.

   Show worked solution

   Step 1: Formula: S_n = (n/2)[2a + (n-1)d]. Step 2: S₂₀ = 10 × [6 + 19 × 4] = 10 × (6 + 76) = 10 × 82 = 820. Answer: 820.
   Modelled on: the A/L Combined Mathematics examination pattern

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Where does Finite series fit in the syllabus?

Year 1 · Term 3