1/2x[1/3+1/6+1/10+....2/x.(x+1)]=1999/2001x1/2
1/2x3+1/3x4+....+1/x(x+1)=1999/4002
1/2-1/3+1/3-1/4+....+1/x-1/x+1=1999/4002
1/2-1/x+1=1999/4002
1/x+1=1/2-1999/4002
1/x+1=1/2001
=>x+1=2001
x=2001-1
x=2000
1/2x[1/3+1/6+1/10+....2/x.(x+1)]=1999/2001x1/2
1/2x3+1/3x4+....+1/x(x+1)=1999/4002
1/2-1/3+1/3-1/4+....+1/x-1/x+1=1999/4002
1/2-1/x+1=1999/4002
1/x+1=1/2-1999/4002
1/x+1=1/2001
=>x+1=2001
x=2001-1
x=2000
tìm x thuộc n biết 1/3+1/6+1/10+...+2/x.(x+1)=1999/2001
tìm x thuộc N biết 1/3+1/6+1/10+...+2/x.(x+1)=1999/2001
Tìm x thuộc N
1\3+1\6+1\10+.....+2\x.(x+1)=1999\2001
Tìm số tự nhiên x biết rằng :1/3+1/6+1/10+...+2/x(x+1)=1999/2001
Tìm x ;
1/3 + 1/6 + 1/10 + ..... + 1/x2+x = 1999/2001
Tìm số tự nhiên x biết rằng 1/3+1/6+1/10+....+2/x(x+1)=1999/2001
tìm x thuộc N biết 1/3+1/6+1/10+...+2/x.(x+1)=1999/2001
Tìm x:
1/3 + 1/6 + 1/10 + 1/15 +...+ 1/x.(2x+1) = 1999/2001
Tìm y :
1/3 + 1/6 + 1/ 10 + ...... + 2/y x ( y + 1 ) = 1999/2001