TO THE RESOLUTION OF PROBLEMS,
127
I
•U »
mn of : à
№ wn ones,
i » be an odd
'-LrM
so s + s 3 — 3s — c x 1 + s — 2, or s 1 — 2s — c X
s z — i, by case 2. Lastly, if n — 9, then m — 4,
and therefore l p s 1 —2 -W 4 —4s*-p 2 — cxs + s 3 — 3s 9
or s 4 — 3s 7, -p l zz c x s 3 —- 2s, case 1.
PROBLEM LXXIV.
Having given the sum f aj, and the sum of the cubes
(b J, of any number of terms in geometrical progression ;
to determine the progression.
By retaining the notation in the last problem, and
proceeding in the same manner, we here have
a — x + xz P xz 1
. + x
>n—1 —
-, and
ic.
we sn
m oAdnum-
the fcCOftl
, have
c into i +
<o tar conti*
best oi them
ber of terms.
equation Je*
if.
. j r or
-jj» 3;
b — x 3 -p x 3 z 3 P x 3 z 6 . . . -\-X 3 Z 5n — 3 —
n3 „371
i&f
Theorem 9. Sect. 10).
Divide the last of these equations by the former, so shall
b z z — l x z 3n — 1 % z 2n ■ + z n -p 1
—= x X --= -t= - = x 7 x - -— be-
a ~3 j y rpi j 2 -f- 2 -f- 1
cause
— 1
— __ s 2 —J— z -p* 1, * and
3n
1
2 1
-p l). Let this equation, and the square of the first
~2 n
a 2 — x z x % ——Η 1 , be now multiplied, cross-
z — 2z "t 1
wise, in order to exterminate x ; whence will be had
s 2ft -P z 11 + 1 ,
2 . - " WIIICII3
2 -+- 2 + 1 J
b Z 2n — 22” + 1 a ^ Z*
— X r = a X
a z — 22+I
the numerators being divided by z n , and the denomi
nators by z, will stand thus,
2 +
z n + 1 +
b x
a* X
Put (as
2 ■+■
z -p 1 -p