\(45\cdot\left(-\frac{5}{7}\right)+9\cdot5+\frac{8}{9}+135+45\cdot\frac{52}{63}\)
\(=-\frac{225}{7}+45+\frac{8}{9}+135+\frac{260}{7}\)
\(=\left(-\frac{225}{7}+\frac{260}{7}\right)+\left(45+135\right)+\frac{8}{9}\)
\(=\frac{35}{7}+180+\frac{8}{9}\)
\(=5+180+\frac{8}{9}\)
\(=185+\frac{8}{9}=185\frac{8}{9}\)
tick đúng cho tớ nha
\(\left(\frac{1}{1\times3}+\frac{1}{3\times5}+\frac{1}{5\times7}+\frac{1}{7\times9}+\frac{1}{9\times11}\right)\times y=\frac{2}{3}\)
Tìm y
1/ Tìm x :
\(\frac{x\times2+5}{x+5}=\frac{6}{4}\)
2/ Tính nhanh :
a) \(\frac{4}{1\times5}+\frac{4}{5\times9}+\frac{4}{9\times13}+\frac{4}{13\times17}+\frac{4}{17\times21}\)
b) \(\left(1-\frac{1}{2}\right)\times\left(1-\frac{1}{3}\right)\times\left(1-\frac{1}{4}\right)\times.......\times\left(1-\frac{1}{2017}\right)\)
c) \(A=2000-5-5-5-.......-5\)( có 200 số 5 )
Tính nhanh
\(\frac{2}{1\times3}+\frac{2}{3\times5}+\frac{2}{5\times7}+\frac{2}{7\times9}+\frac{2}{9\times11}\)
Tính (Theo mẫu):
MẪU\(\frac{9}{10}\times\frac{5}{6}=\frac{9\times5}{10\times6}=\frac{3\times3\times5}{5\times2\times3\times2}=\frac{3}{4}\)\(\frac{3}{4}\)
\(\frac{12}{35}\div\frac{35}{25}\)
\(\frac{9}{22}\times\frac{33}{18}\)
tính :\(\frac{1}{1\times2\times3}+\frac{1}{2\times3\times4}+\frac{1}{3\times4\times5}+\frac{1}{4\times5\times6}+\frac{1}{5\times6\times7}+\frac{1}{6\times7\times8}+\frac{1}{7\times8\times9}+\frac{1}{8\times9\times10}\)
Tính :
A = \(\frac{2}{3\times9}+\frac{5}{9\times24}+\frac{7}{24\times45}+\frac{2}{45\times51}+\frac{11}{51\times84}+\frac{13}{84\times123}\)
\(\frac{4}{9}+\frac{2}{5}-\frac{28}{45}=?\)
\(\frac{24}{75}:\frac{8}{15}\times\frac{10}{9}=?\)
tính bằng cách thuận tiện
a. \(\frac{1}{2}\times\frac{2}{3}\div\frac{4}{3}\times\frac{4}{5}\div\frac{6}{5}\times\frac{6}{7}\div\frac{7}{8}\times\frac{8}{9}\div\frac{10}{9}\)
b.\(\frac{27}{49}\times\frac{49}{50}\times\frac{15}{51}\times(\frac{5}{10}-\frac{1}{2})\)
\(\frac{1}{1\times5}+\frac{1}{5\times9}+\frac{1}{9\times13}+...+\frac{1}{97\times101}\)
