Question

-3,-6 арифметическая прогрессия. найти а25

Answer 1

a(1) = -3

a(2) = -6

d = a(2)-a(1)

d = -6+3 = -3

a(25) = a(1) + 24d

a(25) = -3 + 24*(-3) = -75

Answer 2

To find the 25th term (a25) in the arithmetic progression with a first term of -3 and a common difference of -6, we can use the formula for the nth term of an arithmetic progression:

a_n = a_1 + (n - 1) * d

Where: a_n is the nth term, a_1 is the first term, d is the common difference, and n is the term number we want to find (in this case, n = 25).

Given: a_1 = -3 (first term) d = -6 (common difference) n = 25 (term number)

Now, substitute these values into the formula:

a_25 = -3 + (25 - 1) * (-6) a_25 = -3 + 24 * (-6) a_25 = -3 - 144 a_25 = -147

So, the 25th term (a25) in the arithmetic progression is -147.