Question

A1=15,aпоследнее=105,d=10,n=?

Answer 1

A₁=15  an=105    d=10      n=?
an=a₁+(n-1)*d=15-(n-1)*10=15+10n-10=5+10n=105
10n=100  |÷10
n=10
Ответ: n=10.

Answer 2

In the given arithmetic sequence, we are given:

First term (A1) = 15 Last term (an) = 105 Common difference (d) = 10

To find the value of "n," we can use the formula for the nth term of an arithmetic sequence:

an = A1 + (n - 1)d

Substituting the given values into the formula, we have:

105 = 15 + (n - 1) * 10

Now, let's solve for "n":

105 - 15 = 10n - 10 90 = 10n - 10 100 = 10n n = 100/10 n = 10

Therefore, the value of "n" is 10.