Các câu hỏi tương tự
Tim x
Xem chi tiết
\(\left[\frac{1}{1.2.3}+\frac{1}{2.3.4}+\frac{1}{3.4.5}+..........+\frac{1}{98.99.100}\right].x=\frac{49}{200}\)
tính:A=\(\frac{1}{1.2.3}+\frac{1}{2.3.4}+\frac{1}{3.4.5}+...+\frac{1}{98.99.100}\)
a) \(\frac{1}{1.2}\) + \(\frac{1}{2.3}\)+ \(\frac{1}{3.4}\)+ \(\frac{1}{4.5}\)+ ..... +\(\frac{1}{99.100}\)
b) \(\frac{1}{1.2.3}\)+ \(\frac{1}{2.3.4}\)+ \(\frac{1}{3.4.5}\)+ .......+ \(\frac{1}{98.99.100}\)
\(F=\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+...+\frac{1}{\left(n-1\right)n}=\frac{n-1}{n}\)
\(G=\frac{1}{1.2.3}+\frac{1}{2.3.4}+\frac{1}{3.4.5}+...+\frac{1}{\left(n-1\right)\left(n-1\right).n}=\)
\(H=2+4+6+..+2n=\)
Tìm x biết \(\left(\frac{1}{1.2.3}+\frac{1}{2.3.4}+\frac{1}{3.4.5}+....+\frac{1}{8.9.10}\right).x=\frac{22}{45}\) .
Trả lời:x =
Kèm theo cách làm
tính: \(\frac{1}{1.2.3}+\frac{1}{2.3.4}+\frac{1}{3.4.5}+...+\frac{1}{a\left(a+1\right)\left(a+2\right)}\)
Tính tổng
\(\frac{1}{1.2.3}+\frac{1}{2.3.4}+\frac{1}{3.4.5}+...+\frac{1}{n.\left(n+1\right).\left(n+2\right)}\)
\(\frac{\left(1.2+2.3+3.4+.....+98.99\right)y}{1}=184800\) tim y
2\ \(\left(\frac{1}{1.2.3}+\frac{1}{2.3.4}+\frac{1}{3.4.5}+.....\frac{1}{37.38.39}\right).1428+185,8\) tinh gia tri cua bieu thuc tren
\(\frac{1}{1.2.3}+\frac{1}{2.3.4}+\frac{1}{3.4.5}+...+\frac{1}{n.\left(n+1\right).\left(n+2\right)}\)