1/100.99 - 1/99.98 - 1/98.97 -...- 1/3.2 - 1/2.1
=-(1/100.99 + 1/99.98 + 1/98.97 +...+ 1/3.2 + 1/2.1)
=-(1/2.1+1/3.2 +...+1/98.97+ 1/99.98 +1/100.99 )
=-(1/1.2+1/2.3+1/3.4+...+1/97.98+ 1/98.99 +1/99.100)
=-(1/1-1/2+1/2-1/3+1/3......-1/98+1/98-1/99+1/99-1/100)
=-(1/1-1/100)=-99/100
tính nhanh C=1/100 -1/99 . 98-1/98 . 97-1/97 . 96-...-1/3.2-1/2.1
1. Tính nhanh:
a) 1/1.2 + 1/2.3 + 1/3.4 + .... + 1/2020.2021
b) 1/1.3 + 1/3.5 + 1/5.7 + .... + 1/21.23
c) 1/99 - 1/99 . 98 - 1/98 . 97 - 1/97 . 96 - ... - 1/3.2 -1/2.1
d) 4/1.5 + 4/5.9 + ... + 4/92.96 + 4/96.100
Giúp em với ngày mai em phải nộp zùi🥺
tính nhanh
C= 1/100-1/100.99-1/99.98-1/98-97-...-1/3.2-1/2.1
Tính thuận tiện \(\frac{1}{100\times99}-\frac{1}{99\times98}-\frac{1}{98\times97}-...-\frac{1}{3.2}\)\(-\frac{1}{2.1}\)
C=1/100 - 1/100*99 - 1/99*98 - 1/98*97 - . . . -1/3*2 - 1/2*1
(1/(1x2)/(2x3)/(3x4)):(1/(2x3)/(3x4)/(4x5)):...(1/(97*98)/(98*99)/(99*100))
(1/(1x2)/(2x3)/(3x4)):(1/(2x3)/(3x4)/(4x5)):...(1/(97*98)/(98*99)/(99*100
1/(1x2)/(2x3)/(3x4)):(1/(2x3)/(3x4)/(4x5)):...(1/(97*98)/(98*99)/(99*100
(1/(1x2)/(2x3)/(3x4)):(1/(2x3)/(3x4)/(4x5)):...(1/(97*98)/(98*99)/(99*100
