Question

Tính giá trị biểu thức sau :
\(\frac{1}{2x3}\)+ \(\frac{1}{3x4}\)+ \(\frac{1}{4x5}\)+ ..................+ \(\frac{1}{9x10}\)
Mik đang cần gấp . ai nhanh nhất mik kich cho

Answer 1

\(=1\left(\frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}+...+\frac{1}{9.10}\right)\)

\(=1\left(1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-...+\frac{1}{9}-\frac{1}{10}\right)\)

\(=1-\frac{1}{10}\)

\(=\frac{9}{10}\)

Answer 2

1/2-1/10=2/5

Chúc bạn may mắn@

Answer 3

\(\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+...+\frac{1}{9}-\frac{1}{10}\)

\(=\frac{1}{2}-\frac{1}{10}\)

=\(\frac{2}{5}\)

k nha!