1/21 + 1/28 + 1/36 +...+ 2/x.(x+1) = 2/9
1/21 + 1/28 + 1/36 +...+ 2/x.(x+1) = 2/9
1/21 + 1/28 + 1/36 +...+ 2/x.(x+1) = 2/9
1/21 + 1/28 + 1/36 +...+ 2/x.(x+1) = 2/9
Tìm x biết:
1/21+1/28+1/36+...+2/x.(x+1)=2/9
a,1/1.3+1/3.5+1/5.7+......+1/x+(x+2)=20/41
b,1/3+1/6+1/10+....+1/x.(x+1:2)=2009/2011
c,1/21+1/28+1/36+...+2/x.x+1=2/9
Tìm X:
a,X-20/11x13 - 20/13x15 - 20/15x17-...-20/53x55 = 3/11
b,1/21 + 1/28 + 1/36 + .....+ 2/Xx(X+1) = 2/9
Tim X
a,X - 20/11 x 13 - 20/13 x 15 - 20/15 x 17 -...-20/53 x 55 = 3/11
b,1/21 + 1/28 +1/36 + ... +2/Xx(x + 1) = 2/9
Tìm X:
\(\frac{1}{21}\)+ \(\frac{1}{28}\)+ \(\frac{1}{36}\)+...+ \(\frac{2}{X\times\left(X+1\right)}\)= \(\frac{2}{9}\).
