How do you find the sum of an arithmetic sequence with the last term?

How do you find the sum of an arithmetic sequence with the last term?

The sum of an arithmetic series is found by multiplying the number of terms times the average of the first and last terms. Example: 3 + 7 + 11 + 15 + ··· + 99 has a1 = 3 and d = 4.

What is the formula of sum of last term?

If an is the last term of an arithmetic progression, a is the first term, and n is the total number of terms, then we can use the following formula to find its sum: Sn = n/2 (a1+an).

What is the formula for the sum of an arithmetic series?

“S” is the sum of the arithmetic sequence, “a” as the first term, “d” the common difference between the terms, “n” is the total number of terms in the sequence and….Formula for Sum of Arithmetic Sequence Formula.

Sum of Arithmetic Sequence Formula
When the Last Term is Given S = n⁄2 (a + L)

How do you find the sum of last 20 terms?

  1. Step-by-step explanation:
  2. The A,P series are 3 , 7 , 11 ………… , 407.
  3. The first term = a = 3.
  4. Common difference = d = 7 – 3 = 4.
  5. For n = 407.
  6. ∴ S = 1424.5.
  7. Hence, The sum of 20 terms of A.P is 1424.5 Answer.

How do you find the sum of last 10 terms?

To find the sum of last ten terms, first we need to reverse the given A.P. According to the reverse A.P we have the first term a = 126, common difference (d) = -2, and number of terms (n) = 10. We will put these values in the formula of sum of AP. In this way we can find the sum of the last ten terms of the A.P.

What is the sum of finite arithmetic series?

Sum of an Arithmetic Series For a finite arithmetic sequence given by an=a1+(n−1)d, where a1 is the first term, d is the common difference, and n is the number of terms, the sum of all terms, Sn, can be calculated using the following formula.

Which is the sum of an arithmetic series?

A series is an expression for the sum of the terms of a sequence. For example, 6 + 9 + 12 + 15 + 18 is a series for it is the expression for the sum of the terms of the sequence 6, 9, 12, 15, 18. By the same token, 1 + 2 + 3 + …..100 is a series for it is an expression for the sum of the terms of the sequence 1, 2, 3….100.

What is the sum of the terms of a sequence called?

The sum of the terms of a sequence is called a series. An arithmetic sequence or arithmetic progression is a sequence in which each term is created or obtained by adding or subtracting a common number to its preceding term or value.

Which is the first term of a series?

The first term of series is a and common difference is d. The series is looks like a, a + d, a + 2d, a + 3d, . . . Task is to find the sum of series.

Which is an example of a series in math?

A series is an expression for the sum of the terms of a sequence. For example, 6 + 9 + 12 + 15 + 18 is a series for it is the expression for the sum of the terms of the sequence 6, 9, 12, 15, 18. By the same token, 1 + 2 + 3 +…..100 is a series for it is an expression for the sum of the terms of the sequence 1, 2, 3,……100.

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