1/1.2 +1/2.3 +1/3.4 +....+1/99.100
=1-1/2+1/2-1/3+1/3-14+.....+1/99-1/100
=1-1/100
=99/100
tham khảo
1/1.2 +1/2.3 +1/3.4 +....+1/99.100
=1-1/2+1/2-1/3+1/3-14+.....+1/99-1/100
=1-1/100
=99/100
1/1.2 +1/2.3 +1/3.4 +....+1/99.100
=1-1/2+1/2-1/3+1/3-14+.....+1/99-1/100
=1-1/100
=99/100
tham khảo
1/1.2 +1/2.3 +1/3.4 +....+1/99.100
=1-1/2+1/2-1/3+1/3-14+.....+1/99-1/100
=1-1/100
=99/100
Tìm x biết 1/1x2 + 1/2x3 + 1/3x4 + ... + 1/X(X+1) = 99/100
(1/1x2+1/2x3+1/3x4.....1/7x8+1/8x9)x100-[5/2-(x+206/100)]:1/2=89
A=1x2+2x3+3x4+...+99x100
B=1^2+2^2+...+99^2+100^2
C=5+55+555+...+555...5(có 100 chữ số 5)
A = 1x2 +2x3+3x4+........+99 x 100
B = 1x2x3 + 2x3x4 + 4x5x6 +...........+ 98 x99 x 100
tính A,B
tìm số X, biết
a) 1 / 1x2 + 1 / 2x3 + 1 / 3x4 +....+ 1/(X-1) x X
b) 4/3+(X+3)x2-1/2=19/2+4
c) 1+3+5 + .... + 99 / 2+4+...98+X=1
x/1x2 +x/2x3 + x/3x4+ .....+x/2017x2018=-1
1313/1212 : x = 1/1x2+1/2x3+1/3x4+1/4x5+1/5
1/1x2 + 1/2x3 +1/3x4 +...+ 1/24x25
1/1x2 + 1/2x3 + 1/3x4 +...+ 1/2008x2009