SOLUTION: find the sum of the first 16 terms of the arithmetic progression, if the first term is -5 and the common difference is -6 find the first term and common difference for the seque

Question 694821: find the sum of the first 16 terms of the arithmetic progression, if the first term is -5 and the common difference is -6
find the first term and common difference for the sequence with the given nth term.
an=7.4+0.6n
find the sum: 12+15+18+ . . . +111
a)1887 b)4182 c)369 d)2091

Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
find the sum of the first 16 terms of the arithmetic progression, if the first term is -5 and the common difference is -6
-------
a(16) -5 +(15)(-6) = -95
-----
S(n) = (n/2)(a(1)+a(16))
S(16) = 8(-5-95) = 8(-100) = -800
====================================

find the first term and common difference for the sequence with the given nth term.
an=7.4+0.6n
a(1) = 7.4+0.6 = 8
a(2) = 7.4+0.6*2 = 7.4 = 1.2 = 8.6
----
Common difference = 0.6
--------------------------------
find the sum: 12+15+18+ . . . +111
a(1) = 12 ; d = 3
Find "n" using 111 = 12 + (n-1)3
99 = (n-1)3
n-1 = 33
n = 34
-------
Sum = (34/2)(12+111) = 17*123 = 2091
==================
Cheers,
Stan H.
======================
a)1887 b)4182 c)369 d)2091

RELATED QUESTIONS
In an arithmetic progression, 8th term is 8 and sum of the first 16 terms is 144. Find... (answered by josgarithmetic)

A geometric progression has 6 terms. The first term is 192 and the common ratio is 1.5.... (answered by greenestamps)

The first term of an arithmetic progression is 12 and the sum of the first 16 terms is... (answered by greenestamps)

Find the 6th and 15th terms of the arithmetic progression whose first term is 6 and... (answered by mananth)

A geometric progression has six terms. The first term is 486 and the common ratio is ;.... (answered by greenestamps)

The ninth term of an arithmetic progression is 52 and the sum of the first twelve terms... (answered by srinivas.g)

Find the number of terms in an Arithmetic Progression whose first term is 5 common... (answered by ikleyn)

the sum of the first and last terms of an arithmetic progression is 42.the sum of all the (answered by ikleyn)

The sum of the first twelve terms of an Arithmetic progression is 168. If the third term... (answered by josgarithmetic)