Question

\(\frac{3}{2.5}\)+\(\frac{3}{5.8}\)+\(\frac{3}{8.11}\)+...+\(\frac{3}{17.20}\)

GIÚP MÌNH GIẢI BÀI NÀY NHÉ CÁC BẠN!

Answer 1

Sai đề => Sửa: \(\frac{3}{2.5}+\frac{3}{5.8}+\frac{3}{8.11}+...+\frac{3}{17.20}\)

\(\Rightarrow\frac{1}{2}-\frac{1}{5}+\frac{1}{5}-\frac{1}{8}+\frac{1}{8}-\frac{1}{11}+...+\frac{1}{17}-\frac{1}{20}\)

\(\Rightarrow\frac{1}{2}-\frac{1}{20}\)

\(\Rightarrow\frac{9}{20}\)

Answer 2

nói j chứ trả lời sao đc

Answer 3

dễ ẹt tí nữa làm cho

Answer 4

\(\frac{2}{2.5}+\frac{3}{5.8}+\frac{3}{8.11}+...+\frac{3}{17.20}\)

\(=\frac{2}{2.5}+\left(\frac{3}{5.8}+\frac{3}{8.11}+...+\frac{3}{17.20}\right)\)

\(=\frac{1}{5}+\left(\frac{1}{5}-\frac{1}{8}+\frac{1}{8}-\frac{1}{11}+...+\frac{1}{17}-\frac{1}{20}\right)\)

\(=\frac{1}{5}+\left(\frac{1}{5}-\frac{1}{20}\right)\)

\(=\frac{1}{5}+\frac{1}{5}-\frac{1}{20}=\frac{2}{5}-\frac{1}{20}=\frac{7}{20}\)

Answer 5

9/20

chúc học giỏi

Answer 6

\(\frac{3}{2.5}+\frac{3}{5.8}+\frac{3}{8.11}+...+\frac{3}{17.20}\)

\(=\frac{1}{2.5}+\frac{1}{5.8}+\frac{1}{8.11}+...+\frac{1}{17.20}\)

\(=\frac{1}{2}-\frac{1}{5}+\frac{1}{5}-\frac{1}{8}+...+\frac{1}{17}-\frac{1}{20}=\frac{1}{2}-\frac{1}{20}=\frac{9}{20}\)