Monday

October 20, 2014

October 20, 2014

Posted by **Melissa** on Saturday, December 17, 2011 at 12:46am.

- Math -
**Steve**, Saturday, December 17, 2011 at 6:01amT13 = a+12d = 61

T20 = a+19d = 82

so,

T20-T13 = 7d = 21

d = 3

a = 25

S25 = 25/2 (25 + 25+24*3)

= 25/2 (122) = 25*61 = 1525

**Answer this Question**

**Related Questions**

Can someone help me?! - The 1st, 5th and 13th terms of an arithmetic sequence ...

Maths - 1..The first 2 terms of a geometric progression are the same as the ...

Precalculus - The 8th term in an arithmetic sequence is 5, and the sum of the ...

Maaaaaaaath - the first three terms of an arithmetic sequence are x-2;2x+6 and ...

Math *URGENT - Please give the answers and solutions for each. 1.If the second ...

Maths - An arithmetic and a geometric sequence have the same first terms.(2).......

Math ( Can You check my Work?) - 1.an = 3n - 1 2. an = 2(2n - 3) 3.an = 4^n 4.an...

Math - A sequence is formed by adding together the corresponding terms of a ...

math - the ninth term of an arithmetic sequence is 23 and the 33rd term of the ...

Math for Educators - The first difference of a sequence is 8, 12, 16, 20,... The...