↑は
http://www.math.ust.hk/excalibur/v14_n1.pdf のp.3に出てた。orz
しかたないので一題・・・
Problem 2.
Let a_1 〜 a_5 be real numbers satisfying the following equations:
a_1/(1+k^2) + a_2/(2+k^2) + a_3/(3+k^2) + a_4/(4+k^2) + a_5/(5+k^2),
for k=1〜5. Find the value of
a_1/37 + a_2/38 + a_3/39 + a_4/40 + a_5/41,
(Express the value in a single fraction.)
>>850 結果だけ並べると・・・
a_1 = 1105/72,
a_2 = -2673/40,
a_3 = 1862/15,
a_4 = -1885/18,
a_5 = 1323/40,
より
b_6 = 187465/(3*37*38*39*41) ≒ 1.00061649483987・・・ / 36,
b_7 = 1197/(5*13*17*53) ≒ 1.00150260394436・・・ / 49,
b_8 = 85345/(16*13*17*23*67) ≒ 1.00240485551780・・・ / 64,
b_9 = 277289/(9*17*41*43*83) ≒ 1.00321917612728・・・ / 81,
b_10=12117378/(3*25*7*13*17*101*103) ≒ 1.00391855290609・・・ / 100,
b_0 = 13489 / 3600 ≒ 3.74694444444444・・・
ここに b_k = a_1/(1+k^2) + a_2/(2+k^2) + a_3/(3+k^2) + a_4/84+k^2) + a_5/(5+k^2),