Question

Tìm x biết: \(\frac{1}{5X8}+\frac{1}{8X11}+\frac{1}{11X14}+.....+\frac{1}{xX\left(x+3\right)}=\frac{101}{1540}\)

 

Answer 1

toán 6 hả

X3 lên nhé

Answer 2

X3 lên

Answer 3

nhân cả tử và mẫu cho 3 là làm đc thôi

Answer 4

\(\frac{1}{5.8}+\frac{1}{8.11}+\frac{1}{11.14}+....+\frac{1}{x.\left(x+3\right)}=\frac{101}{1540}\)

\(\Leftrightarrow\frac{1}{3}\cdot\left(\frac{1}{5}-\frac{1}{8}+\frac{1}{8}-\frac{1}{11}+\frac{1}{11}-\frac{1}{14}+....+\frac{1}{x}-\frac{1}{x+3}\right)=\frac{101}{1540}\)

\(\Leftrightarrow\frac{1}{5}-\frac{1}{x+3}=\frac{101}{1540}\div\frac{1}{3}\)

\(\Leftrightarrow\frac{1}{5}-\frac{1}{x+3}=\frac{303}{1540}\)

\(\Leftrightarrow\frac{1}{x+3}=\frac{1}{5}-\frac{303}{1540}\)

\(\Leftrightarrow\frac{1}{x+3}=\frac{1}{308}\)

\(\Rightarrow x=308-3=305\)

Answer 5

cảm ơn 

Answer 6

cảm ơn bạn nhé

Answer 7

x3 lên