tìm x
1/2.1+1/2.3+1/3.4+1/4.5+.....+1/x(x+1)
Tìm X biết 2/2.3 + 2/3.4 + 2/4.5+...... +2/X(X+1) = 2007/2009
TÌM x THUỘC N:2/2.3+2/3.4+2/4.5+....+2/x.(x+1)=1999/2001
Tìm x khác 0, biết :\(1/2.3+1/3.4+1/4.5+1/5.6+...+1/19.20=18/x\)
tìm x:1/2.3+1/3.4+1/4.5+...+1/x.(x+1)=16/51
1+2.(1/2.3+1/3.4+1/4.5+...+1/x.(x+1)=3/2
tìm x biết \(\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}+...+\frac{1}{x.\left(x+1\right)}=\frac{2019}{2020}\)
giúp mìn với 1/1.2 +1/2.3+1/3.4+1/4.5+....+1/[x-1].x+1/x.[x+1]
tìm x biết : \(\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}+.....+\frac{1}{x\left(x+1\right)}=\frac{17}{18}\)
