Tính E = 1/1.2-1/1.2.3+1/2.3-1/2.3.4+1/3.4-1/3.4.5+...+1/99.100-1/99.100.101
A = 1/2.3.4 +1/2.3.4.5 + 1/3.4.5.6 + ... +1/47.48.49.50
B= 1/1.2+1/1.2.3 - 1/2.3.4 + 1/.3.4 -1/3.4.5 ... +1/99.100 - 1/99.100.101
M = \(\frac{1}{1.2}\)-\(\frac{1}{1.2.3}\)+\(\frac{1}{2.3}\)-\(\frac{1}{2.3.4}\)+...+\(\frac{1}{99.100}-\frac{1}{99.100.101}\)
tìm x biết :
1/1.2.3 + 1/2.3.4 + 1/3.4.5 + ... +1/98.99.100 = 1/x .(1/1.2 - 1/99.100)
ai ơi thương tôi với
rối cuộc thì x = bao nhiu!!!!!!!!!!!!!!!!!!!!!!
A =1+1/1.2.3+1/2.3.4+...+1/98.99.100 . Biết 8A = 1/k .(1/1.2-1/99.100)tìm k
1/1.2.3+1/2.3.4+...+1/98.99.100=k.(1/1.2-1/99.100)
tìm k biết :
1/1.2.3 + 1/2.3.4 + 1/3.4.5 + ... +1/98.99.100 = 1/k ( 1/1.2 - 1/99.100 )
1/1.2.3+1/2.3.4+1/3.4.5+...+1/98.99.100=1/k.(1/1.2-1/99.100)
Vậy k=...
Tính tổng:
A=1.2.3+2.3.4+3.4.5+...…+99.100.101
B=1.2+3.4+51.6+…+99.100
C=1.3+3.5+5.7+…+97.99
D=1.3.5+3.5.7+…+95.97.99
