The question is, using a graphing calculator solve the sum of this sequence.
{-3.12n+4.69},n=25
My calculator is an HP 49g + and I still can't figure this thing out.
2007-07-30 13:56:17 · 4 answers · asked by Anonymous in Science & Mathematics ➔ Mathematics
SORRY, THE EQUATION IS {3.11n+4.64} n=21
2007-07-30 14:04:32 · update #1
The sum of the 25 first terms in the sequence is -896.75 if i understood the sum right...
another way to do this is to break the sum into two parts and use the proporties of sums:
Sum(-3.12*n, from 1 to 25) + Sum (4.69, from 1 to 25) = -3.12*Sum(n, from 1 to 25) + 4.69*25=
-3.12*[n(n+1)/2 and n=25] +117.25=
-3.12*[25*26/2]+117.25=
-3.12*325+117.25=
-1014+117.25= -896.75
Ok, i just saw the new equation... doing exactly as above you get 815.85... that is the sum of the 21 first terms in the sequence..
2007-07-30 14:10:15 · answer #1 · answered by jsos88 2 · 0⤊ 0⤋
The sum is n(2t1+(n-1)d)/2
Here t1 = 7.75 d = 4.64, n= 21
So sum = 21(2*7.75+ 21*(4.64))/2 = 1185.87
2007-07-30 21:15:03 · answer #2 · answered by ironduke8159 7 · 0⤊ 0⤋
"I don't have a calculator"
--Instant Yahoo Answers Solid Gold Classic Response
2007-07-30 21:04:08 · answer #3 · answered by Mr. Vincent Van Jessup 6 · 0⤊ 2⤋
I think it's negative seventy-three and thirty-one hundredths:
-73.31
The second one is 69.95.
2007-07-30 21:05:43 · answer #4 · answered by I vote Capt. America 3 · 1⤊ 0⤋