Question

3/11x6 + 3/16x21 + 3/21x26  +  ........+3/61 x 66  tính
~ ai nhanh mik t cho nha . 

Answer 1

nhìn tớ

obichisTổng điểm: 456Số kỹ năng đã thực hành: 8Điểm hỏi đáp: Tổng: 10000000000000. Tuần này: 1000000Xuất sắc(100 điểm):775

Answer 2

Ta có:

\(\frac{3}{11.16}+\frac{3}{16.21}+\frac{3}{21.26}+...+\frac{3}{61.66}\)

\(=\frac{1}{5}.\left(\frac{1}{11.16}+\frac{1}{16.21}+\frac{1}{21.26}+...+\frac{1}{61.66}\right)\)

\(=\frac{1}{5}.\left(\frac{1}{11}-\frac{1}{16}+\frac{1}{16}-\frac{1}{21}+\frac{1}{21}-\frac{1}{26}+...+\frac{1}{61}-\frac{1}{66}\right)\)

\(=\frac{1}{5}.\left(\frac{1}{11}-\frac{1}{66}\right)=\frac{1}{5}.\frac{5}{66}\)

\(=\frac{1}{66}\)

Answer 3

\(\frac{3}{11x16}+\frac{3}{16x21}+\frac{3}{21x26}+.........+\frac{3}{61x66}\)

= \(\frac{3}{11}-\frac{3}{16}+\frac{3}{16}-\frac{3}{21}+\frac{3}{21}-\frac{3}{26}+..........+\frac{3}{61}-\frac{3}{66}\)

=> \(\frac{3}{11}-\frac{3}{66}\)= \(\frac{5}{22}\)

Answer 4

Sửa đề : \(\frac{3}{11.16}+\frac{3}{16.21}+\frac{3}{21.26}+...+\frac{3}{61.66}\)

\(=\frac{3}{5}\left(\frac{1}{11}-\frac{1}{16}+\frac{1}{16}-\frac{1}{21}+\frac{1}{21}-\frac{1}{26}+...+\frac{1}{61}-\frac{1}{66}\right)\)

\(=\frac{3}{5}\left(\frac{1}{11}-\frac{1}{66}\right)\)

\(=\frac{3}{5}.\frac{5}{66}\)

\(=\frac{1}{22}\)