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exis [7]
3 years ago
7

What is the sum of the first 20 terms of the series 3 + 14 + 25 + 25 + 36 +

Mathematics
2 answers:
Fynjy0 [20]3 years ago
6 0

Answer:

S _{20} = 2150

Step-by-step explanation:

a _{1} = 3 \\ a _{2} = 14 \\ d = a _{2} - a_{1}  = 14 - 3 = 11 \\ n = 20

S _{n} =  \frac{n}{2} (2a + (n - 1)d) \\  \\ S _{20} =  \frac{20}{2} (2(3) + (20 - 1) \times 11) \\  \\ S _{20} = 10 \times (6 + 19 \times 11) \\ S _{20} = 10 \times (6 + 209) \\ S _{20} = 10 \times 215 \\ S _{20} = 2150

Luba_88 [7]3 years ago
5 0
2150 is the correct answer
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