Question 12
Sequences and SeriesFind the sum of the first 20 terms of the sequence −7, −3, 1, ….
- A.620
- B.660
- C.690
- D.1240
Show the answer and explanation
Answer: A (620)
Explanation
a = −7, d = 4. S₂₀ = 10[2(−7) + 19(4)] = 10 × 62 = 620.
Find the sum of the first 20 terms of the sequence −7, −3, 1, ….
Answer: A (620)
a = −7, d = 4. S₂₀ = 10[2(−7) + 19(4)] = 10 × 62 = 620.