"An equation for me has no meaning, unless it expresses a thought of God."
--Srinivasa Ramanujan
Good day good citizens
🙂
Leo ni siku nzuri ya hesabu na leo nataka tuongelee infinite series yaani sum ya sequence ya namba zisizo na mwisho
Post yangu iliyopita niliongelea maana ya series na aina za series
Sasa hivi nataka kuonesha kuwa series ya mjumuliso wa namba zote sio divergent bali ni convergent (refer to last post)
Yani S=1+2+3+4+5....tukiendelea kujumlisha hivi mpaka milele tutapata jibu la -1/12
Proof:
ili kuprove hii kitu inabidi tuanze kujua series moja inaitwa grandi's series
Ambayo ipo hivi
X=1-1+1-1+1-1+1-1.....∞
Ukiangalia hiyo sequence kadri unapoendelea kujumlisha moja na kutoa moja popote utakaposimama jibu linakuja either 0 au 1
Hivyo kwakuwa sequence inaenda mpaka infinity na hatujui infinity itasimamia wapi basi jawabu la hii series inaonekana kuwa ni kati ya 0 na 1 hivyo tunasema jibu ni 0.5 au 1/2
Hivyo hii series ina converge to 1/2
X=1-1+1-1+1-1...∞ = 1/2
X=1/2
Pia tuangalie series nyingine
Y=1-2+3-4+5-6+7-8+9....∞
Hii series mara mbili ni sawa na 2Y
2Y = Y + Y
Hivyo tuzijumlishe hizi series kwa zenyewe
1-2+3-4+5-6+7-8+9....
+ 1-2+3-4+5-6+7-8.....
=1-1+1-1+1-1+1-1....
Kwahiyo
2Y=1-1+1-1+1-1....
Lakini kumbuka X = 1-1+1-1+1-1+1...
So
2Y = X
2Y = 1/2
Y = 1/4
Sasa turudi Kwenye series yetu tuiite S
S= 1+2+3+4+5+6.....+∞
Kumbuka Y = 1-2+3-4+5-6+7...∞
Tutafute S - Y = ?
S - Y =
1+2+3+4+5+6+7+8+9+10..
- [1-2+3-4+5-6+7-8+9-10...]
=4+8+12+16+20....∞
Ukiangalia hizo namba ni multiples za 4
Kwahyo 4 tunaweza kuitoa nje ikawa
=4(1+2+3+4+5...∞)
Lakini 1+2+3+4...∞ = S
= 4S
Hivyo
S - Y = 4S
Kumbuka Y = 1/4
Hivyo
S - 1/4 = 4S
-1/4 = 3S
3S = -1/4
Therefore
S = - 1/12
Hivyo 1+2+3+4+5....∞ = -1/12
Pioneered by Srinivasa Ramanujan mwanamahesabu wakihindi aliyetokea familia masikini bila kwenda shule na kujifundisha hesabu mwenyewe mpaka kugundua vitu vikubwa Kwenye pure mathematics.