Sum of first n terms of an arithmetic sequence is `8n^2`+5n. Find the sum of first 20 terms.

The sum of first n terms of an arithmetic sequence is n^2+2n What is the sum of first 20 terms of this sequence?

The sum of first 9 terms of an arithmetic sequence is 45 and the sum of first 18 terms is 171. Find the sum of 5^(th) to 14^(th) terms.

The sum of first 9 terms of an arithmetic sequence is 45 and the sum of first 18 terms is 171. Find its 14^(th) term.

The sum of first 9 terms of an arithmetic sequence is 45 and the sum of first 18 terms is 171. What is its 5^(th) term?

The sum of first 9 terms of an arithmetic sequence is 45 and the sum of first 18 terms is 171. What is the sum of its 10^(th) to 18^(th) terms?

The sum of first 9 terms of an arithmetic sequence is 45 and the sum of first 18 terms is 171 a) What is the sum of its 10^(th) to 18^(th) terms? b) What is its 5^(th) term? c) Find its 14^(th) term. d). Find the sum of 5^(th) to 14^(th) terms.

Sum of first 9 terms of an arithmetic sequence is 261, and the sum of next 6 terms is 444. i)- Find the first term and common difference. ii) Write the algebraic form of the sequence: iii) Write the algebraic.form of the sum.

The sum of first n terms of an arithmetic sequence is n^2+2n What is the first term?

The sum of first n terms of an arithmetic sequence is n^2+2n Find the common difference.

The sum of first n terms of an arithmetic sequence is n^2+2n Prove that the sum of continuous terms starting from the first of the sequence 3,5,7,..... added to 1 gives a perfect square.