Tính dãy

To find the sum of the given sequence, we can use the formula for the sum of an arithmetic series:

Sn = (n/2)(a1 + an)

Where Sn is the sum of the series, n is the number of terms, a1 is the first term, and an is the last term.

In this case, the first term (a1) is 1, the last term (an) is 99, and the common difference (d) is 2 (since each term increases by 2).

We can find the number of terms (n) by using the formula for the nth term of an arithmetic series:

an = a1 + (n-1)d

99 = 1 + (n-1)2
99 = 1 + 2n - 2
99 = 2n - 1
2n = 100
n = 50

Now we can substitute the values into the sum formula:

Sn = (n/2)(a1 + an)
Sn = (50/2)(1 + 99)
Sn = 25(100)
Sn = 2500

Therefore, the sum of the given sequence is 2500.