Question

Арифметическая прогрессия задана условием an = −11,9 + 7,8n . Найдите a11.

Answer 1

7.8 x 11 = 85.8

тк - 11,9 c минусом , то -11,9 + 85,8 = 73.9

Answer 2

To find the 11th term (a11) of the arithmetic progression, we can use the formula for the nth term of an arithmetic progression:

an = a1 + (n - 1) * d

where: an = nth term (in this case, a11) a1 = first term of the arithmetic progression n = term number (in this case, n = 11) d = common difference between consecutive terms

From the given condition, we have:

an = -11.9 + 7.8n

Now, let's find the common difference (d):

a2 = -11.9 + 7.8 * 2 = -11.9 + 15.6 = 3.7

Now that we know the common difference (d = 3.7), we can find a1 by substituting n = 2 into the given formula:

a2 = a1 + (2 - 1) * 3.7 3.7 = a1 + 3.7 a1 = 0

Now, we have a1 = 0 and d = 3.7, we can find a11:

a11 = a1 + (11 - 1) * 3.7 a11 = 0 + 10 * 3.7 a11 = 0 + 37

Therefore, the 11th term (a11) of the arithmetic progression is 37.