1/1.2.3+1/2.3.4+...+1/98.99.100
=1/2.(1/1.2-1/2.3)+1/2.(1/2.3-1/3.4)+...+1/2.(1/98.99-1/99.100)
=1/2.(1/1.2-1/2.3+1/2.3-1/3.4+...+1/98.99-1/99.100)
=1/2.(1/2-1/9900)=1/2.4949/9900=4949/19800
1/1*2 - 1/2*3 - 1/3*4- ..... -1/98*99=1/100+1/99*100
1/1*2 1/2*3 1/3*4 ..... -1/98*99=1/100 1/99*100
cho T = 1/2 + 1/3 + 1/4 +....+ 1/99 + 1/100 và M = 1/99 + 2/98 + 3/97 + ...+ 97/3 + 98/2 +99/1
hãy tìm tỉ số T/M
Tính
1/1*2 +1/2*3 + 1/3*4 + ..........+1/98*99 + 1/99*100
a)A=1-2+3-4+...+99-100
b)B=1-2-3+4+5-6-7+...+97-98-99+100
c)C=2100-299s-998-...-22-2-1
giup mik vs a
C=(1/2+1/3+ 1/4+... +1/100): (99/1 + 98/2 + 97/3 ... +1/99)
tìm C
C=1/100 - 1/100*99 - 1/99*98 - 1/98*97 - . . . -1/3*2 - 1/2*1
Tính:(101+100+99+98+...+3+2+1)/(101-100+99-98+...+3-2+1)
Tính
P= 1/1*2*3 + 1/2*3*4 + 1/3*4*5 +........+1/98*99*100
