Question

M = 1/1+2 + 1/1+2+3 + 1/1+2+3+4 + 1/1+2+3+4+5

Answer 1

\(M=\frac{1}{3}+\frac{1}{6}+\frac{1}{10}+\frac{1}{15}\)

\(M=\frac{2}{6}+\frac{2}{12}+\frac{2}{20}+\frac{2}{30}\)

\(M=\frac{2}{2.3}+\frac{2}{3.4}+\frac{2}{4.5}+\frac{2}{5.6}\)

 \(M=2\left(\begin{cases}1\\2\end{cases}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+\frac{1}{5}-\frac{1}{6}\right)\)

\(M=2.\frac{1}{3}\)

\(M=\frac{2}{3}\)

Nếu đúng thì tk cho mình nhé <33

Answer 2

2/3 nha bạn hoặc 2.1/3