Question

Thực hiện phép tínhPhép nhân nhé các bạnB = \(\frac{1}{1.5}+\frac{1}{5.9}+\frac{1}{9.13}+...+\frac{1}{41.45}.\)

Answer 1

\(B=\frac{1}{1.5}+\frac{1}{5.9}+...+\frac{1}{41.45}\)

\(4B=1-\frac{1}{5}+\frac{1}{5}-\frac{1}{9}+...+\frac{1}{41}-\frac{1}{45}\)

\(4B=\frac{44}{45}\)

\(B=\frac{11}{45}\)

Answer 2

\(B=\frac{1}{1.5}+\frac{1}{5.9}+...+\frac{1}{41.45}\)

\(=\frac{1}{4}.\left(\frac{4}{1.5}+\frac{4}{5.9}+...+\frac{4}{41.45}\right)\)

\(=\frac{1}{4}.\left(1-\frac{1}{5}+\frac{1}{5}-\frac{1}{9}+...+\frac{1}{41}-\frac{1}{45}\right)\)

\(=\frac{1}{4}.\left(1-\frac{1}{45}\right)\)

\(=\frac{1}{4}.\frac{44}{45}\)

\(=\frac{11}{45}\)

Answer 3

\(B=\frac{1}{1.5}+\frac{1}{5.9}+\frac{1}{9.13}+...+\frac{1}{41.45}\)

= \(1-\frac{1}{5}+\frac{1}{5}-\frac{1}{9}+\frac{1}{9}-\frac{1}{13}+...+\frac{1}{41}-\frac{1}{45}\)

= \(1-\frac{1}{45}\)

= \(\frac{45}{45}-\frac{1}{45}\)

= \(\frac{44}{45}\)

Chúc bạn học tốt !!!

Answer 4

\(B=\frac{1}{1\cdot5}+\frac{1}{5\cdot9}+\frac{1}{9\cdot13}+...+\frac{1}{41\cdot45}\)

\(B=\frac{1}{4}\left(\frac{4}{1\cdot5}+\frac{4}{5\cdot9}+\frac{4}{9\cdot13}+...+\frac{4}{41\cdot45}\right)\)

\(B=\frac{1}{4}\left(\frac{1}{1}-\frac{1}{5}+\frac{1}{5}-\frac{1}{9}+\frac{1}{9}-\frac{1}{13}+...+\frac{1}{41}-\frac{1}{45}\right)\)

\(B=\frac{1}{4}\left(1-\frac{1}{45}\right)\)

\(B=\frac{1}{4}\cdot\frac{44}{45}\)

\(B=\frac{11}{45}\)

Answer 5

\(B=\frac{1}{1\cdot5}+\frac{1}{5\cdot9}+\frac{1}{9\cdot13}+...+\frac{1}{41\cdot45}\)

\(B=\frac{1}{4}\left(\frac{4}{1\cdot5}+\frac{4}{5\cdot9}+\frac{4}{9\cdot13}+...+\frac{4}{41\cdot45}\right)\)

\(B=\frac{1}{4}\left(\frac{1}{1}-\frac{1}{5}+\frac{1}{5}-\frac{1}{9}+\frac{1}{9}-\frac{1}{13}+...+\frac{1}{41}-\frac{1}{45}\right)\)

\(B=\frac{1}{4}\left(1-\frac{1}{45}\right)\)

\(B=\frac{1}{4}\cdot\frac{44}{45}\)

\(B=\frac{11}{45}\)

Answer 6

Mình nhầm nhé 5-1=4 thiếu 4 nên 

\(\frac{1}{4}.\left(1-\frac{1}{45}\right)\)

= \(\frac{11}{45}\)

Answer 7

bài này tui lp 6 cx lm đc r