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Anika [276]
3 years ago
11

How many terms of the arithmetic sequence {-4,-2, 0, ....} will give a sum of 500?

Mathematics
1 answer:
IrinaK [193]3 years ago
3 0

Answer:

a. 25

Step-by-step explanation:

Sₙ = n/2 * (2 * a₁ + (n-1) * d)

Sₙ = 500     a₁ = -4    d = 2

500 = n/2 * (-8 + (n-1) * 2) = n/2 * (-8 + 2n - 2) = n/2 * (2n - 10) = n² -5n

n² - 5n -500 = 0

(n - 25) (n + 20) = 0

n > 0

n = 25

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See attachment

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