25 Июн 2019 в 19:44
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Ответы
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To solve this problem, we need to find the value of "n" that makes the sum of the series equal to 1456.

The given series is an arithmetic series with a common difference of 2. The sum of an arithmetic series is given by the formula:

S = n/2 * (a + l)

Where:
S = Sum of the series
n = Number of terms
a = First term
l = Last term

In this case:
a = 25
l = 2n - 1
S = 1456

Plugging in the values, we get:

1456 = n/2 * (25 + 2n - 1)

1456 = n/2 * (24 + 2n)

1456 = n(24 + 2n) / 2

2912 = 24n + 2n^2

Rearranging the equation to form a quadratic equation:

2n^2 + 24n - 2912 = 0

Dividing by 2:

n^2 + 12n - 1456 = 0

Factoring the quadratic equation:

(n + 44)(n - 32) = 0

n = -44 or n = 32

Since the number of terms cannot be negative, n = 32 is the valid solution.

Therefore, the sum of the series 25 + 27 + 29 + ... + (2n - 1) equals 1456 when n = 32.

21 Апр 2024 в 00:42
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