SOLUTION: 1st question: If the sum of the first two terms of an arithmetic sequence equals the sum of the first three terms,find the sum of the first five terms. 2nd question: the terms

Question 1197635: 1st question:
If the sum of the first two terms of an arithmetic sequence equals the sum of the first three terms,find the sum of the first five terms.
2nd question:
the terms a,m,n,b form an arithmetic sequence.Express m and n in terms of a and b.(The terms m and n are arithmetic means of the terms a and b.)
Method I 've tried: d=(b-a)/3
3rd question:
Is y,x+2y,2x+3y....an arithmetic sequence?If it is,find the sum of the first 100 terma.
Method I 've tried:yes,because d=a2-a1=x+2y-y=x+y a3-a2=(2x+3y)-(x+2y)=x+y ,
but i do not know how to count the sum.
4th question:
A bank loan of $8000 is repaid in annual payments of $1000plus 10% interest on the unpaid balance.What is the total amount of interest paid?
5th question:
In preparing a bid for constructing a new building,a contractor determines that the foundation and basement will cost $605000 and the first floor will cost $360000.Each floor above the first will cost $15000 more than the one below it.How much will the building cost if it is to be 18 floors high?
Thank you.
Answer by greenestamps(13200) (Show Source): You can put this solution on YOUR website!

ONE question per post.

Your first three questions are on the same subject, so you could post them together; however, they really should be posted separately.

The other two questions are on completely different topics and MUST be posted separately.

Re-post the questions one at a time, as the posting instructions say....

RELATED QUESTIONS
In an arithmetic sequence, the sum of the first three terms is 18 and the sum of the... (answered by Theo)

The sum of the first n terms of an arithmetic squence is given by the formula; Sn= n/2... (answered by edjones)

the 15th term in an arithmetic sequence is 129 and the sum of the first fifteen terms is... (answered by josgarithmetic,greenestamps)

The sum of the first n terms of an arithmetic sequence is n(3n + 11)/2 . a) Find its 1st (answered by Fombitz)

What are the first three terms if the 11th term of an arithmetic sequence is 60 and the... (answered by Edwin McCravy)

The first two terms of a geometric sequence and an arithmetic sequence are the same. The... (answered by Edwin McCravy)

The 11th term of an arithmetic sequence is 57 and the sum of the first and fourth terms... (answered by MathTherapy)

Find three consecutive terms of an arithmetic sequence, if the sum of the first and... (answered by Edwin McCravy)

The sum of the first nine terms of an arithmetic function is 81. if the sum of the first... (answered by greenestamps)