\(\frac{1}{2x3}+\frac{1}{3x4}+\frac{1}{4x5}+...+\frac{1}{98x99}\)
\(=\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+...+\frac{1}{98}-\frac{1}{99}\)
\(=\frac{1}{2}-\frac{1}{99}\)
\(=\frac{99}{198}-\frac{2}{198}\)
\(=\frac{97}{198}\)
\(\frac{A}{198}=\frac{97}{198}=>A=198x97:198=97\)
tính tổng: 1/1x2 + 1/2x3 + 1/ 3x4 +...+ 1/98 x 99 + 1/99 x 100
Tìm số tự nhiên a biết 1/2x3+1/3x4+1/4x5+......+1/a x(a+1)=49/100
tim a biet 1/2x3 + 1/3x4 + 1/4x5 +....+1/ax(a+1)=299/600
(x+1/2x3)+(X+1/3x4)+(X+1/4x5)+(X+1/5x6)=25/3
tìm a biết 1/2x3+ 1/3x4+1/4x5 +...+1/ax(ax1)=49/100
Tìm số tự nhiên A biết : 1/2X3+ 1/3X4+1/4X5+...+1/Ax(a+1)=49/100
1/2x3+1/3x4+1/4x5+....+1/99x100=?
1/2x3 + 1/3x4 + 1/4x5 + ... + 1/9x10 = ?
1/2x3+1/3x4+1/4x5+,.......+1/29x30
