arithmetic progression

posted by .

An arithmetic progression has 3 as its first term. Also, the sum of the first 8 terms is twice the sum of the first 5 terms. Find the common difference.

• arithmetic progression -

2[(5 * 3) + 10d] = (8 * 3) + 28d

• arithmetic progression -

sum(8) = 4(2a + 7d)
= 8a + 28d = 24 + 28d
sum(5) = (5/2)(2a + 4d)
= 5a + 10d
= 15 + 10d

24+28d = 2(15+10d)
solve for d, let me know what you get

Similar Questions

1. arithmetic

Two arithmetic progression have thd same first and last terms.the first arithmetic progression has 21 terms with a common difference of 9.How many terms has the other arithmetic progression if its common difference is 4?
2. arithmetic

an arithmetic progression has 20 terms. the sum of all the even terms is 350. given that the first term is 5, find the common difference and the eleventh term.
3. maths

1) The first term of arithmetic progression is -20 and the sum of it's term is 250. find it's last term if the number of it's terms is 10 2) Find the fifth term from the arithmetic progression -12, -9, -6 hence find the sum of it's …
4. Maths

1..The first 2 terms of a geometric progression are the same as the first two terms of an arithmetic progression.The first term is 12 and is greater than the second term.The sum of the first 3 terms od the arithmetic progression is …
5. Mathematics

The 25 term of an Arithmetic Progression is 7 1/2 and the sum of the first 23 terms is 98 1/2. Find the i. 1st term ii. common difference iii. sum of the first 30 terms
6. math

The first, the third and the seventh terms of an increasing arithmetic progression are three consecutive terms of a geometric progression. In the first term of the arithmetic progression is 10 find the common difference of the arithmetic …
7. arithmetic

in an arithmetic progression the 13th term is 27 and the 7th term is three times the second term find;the common difference,the first term and the sum of the first ten terms
8. algebra

if 1, 2, 7 and 20, respectively, are added to the first terms of an arithmetic progression, a geometric progression of four terms is obtained. find the first term and common difference of the arithmetic progression the answers are …
9. math

An arithmetic progression as the same first and second terms as the geometric progression. Find the sum of the first 20 terms of the arithmetic progression. How do I do this?
10. math C2 sequences and series

The eight,fourth and second terms of an arithmetic progression form the first three terms of a geometric series. The arithmetic progression has first term A and common difference d, and the geometric progression has first term G and …

More Similar Questions