A1= 2 An=87 Sn=801. Найти: d и n

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вопрос

Given
A1 =
An = 8
Sn = 801

First, find the common difference, d:

An = A1 + (n-1)
87 = 2 + (n-1)
85 = (n-1)d

Next, find the number of terms, n, using the sum formula:

Sn = n/2 (A1 + An
801 = n/2 (2 + 87
801 = n/2 * 8
n/2 = 801/8
n = 18

Now substitute n = 18 into the equation 85 = (n-1)d to find d:

85 = (18-1)
85 = 17
d = 85/1
d = 5

Therefore, the common difference, d, is 5 and the number of terms, n, is 18.