Tính bằng cách thuận tiện nhất:
a)\(\frac{21}{11}\times\frac{22}{17}\times\frac{68}{63}\)
b) \(\frac{5}{14}\times\frac{7}{13}\times\frac{26}{25}\)
K
Khách
Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
Những câu hỏi liên quan
1 tháng 2 2019
a,\(\frac{21}{25}.\frac{11}{9}.\frac{5}{7}=\frac{21.11.5}{25.9.7}=\frac{3.7.11.5}{5^2.3^2.7}=\frac{11}{5.3}=\frac{11}{15}\)
b,\(\frac{5}{23}.\frac{17}{26}+\frac{5}{23}.\frac{9}{26}=\frac{5}{23}.\left(\frac{17}{26}+\frac{9}{26}\right)=\frac{5}{23}.1=\frac{5}{23}\)
c, \(\left(\frac{3}{29}-\frac{1}{5}\right).\frac{29}{3}=\frac{3}{29}.\frac{29}{3}-\frac{1}{5}.\frac{29}{3}=1-\frac{29}{15}=-\frac{14}{15}\)
TD
1 tháng 2 2019
a , \(\frac{21}{25}\times\frac{11}{9}\times\frac{5}{7}\)
\(=\frac{21\times11\times5}{25\times9\times7}\)
\(=\frac{3\times7\times11\times5}{5\times5\times3\times3\times7}\)
\(=\frac{11}{5\times3}\)
\(=\frac{11}{15}\)
b , \(\frac{5}{23}\times\frac{17}{26}+\frac{5}{23}\times\frac{9}{26}\)
\(=\frac{5}{23}\times\left(\frac{17}{26}+\frac{9}{26}\right)\)
\(=\frac{5}{23}\times\frac{26}{26}\)
\(=\frac{5}{23}\times1\)
\(=\frac{5}{23}\)
c , \(\left(\frac{3}{29}-\frac{1}{5}\right)\times\frac{29}{3}\)
\(=\frac{3}{29}\times\frac{29}{3}-\frac{1}{5}\times\frac{29}{3}\)
\(=1-\frac{29}{15}\)
NN
30 tháng 4 2016
a) (21x11x2x17x4)/(11x17x21x3)
=(21x11x2x17x4)/(11x17x21x3)
=8/3
b) (5x7x13x2)/(7x2x13x5x5)
=1/5
DP
8 tháng 5 2017
\(\frac{21}{11}\times\frac{22}{17}\times\frac{68}{63}=\frac{21\times22\times68}{11\times17\times63}\)
\(=\frac{7\times3\times11\times2\times17\times4}{11\times17\times7\times9}=\frac{24}{9}=\frac{8}{3}\)
\(\frac{5}{14}\times\frac{7}{13}\times\frac{26}{25}=\frac{5\times7\times26}{14\times13\times25}\)
\(=\frac{5\times7\times2\times13}{7\times2\times13\times5\times5}=\frac{1}{5}\)
8 tháng 5 2017
\(\frac{21}{11}.\frac{22}{17}.\frac{68}{63}=\frac{21.22.68}{11.17.63}=\frac{21.2.11.4.17}{11.17.21.3}=\frac{\left(17.11.21\right).2.4}{\left(11.17.21\right).3}=\frac{2.4}{3}=\frac{8}{3}\)
\(\frac{5}{14}.\frac{7}{13}.\frac{26}{25}=\frac{5.7.26}{14.13.25}=\frac{5.7.13.2}{2.7.13.4.5}=\frac{\left(5.7.13.2\right)}{\left(5.7.13.2\right).5}=\frac{1}{5}\)
15 tháng 5 2017
a) 11x2x17x4x21/11x17x63=8/3
b)5x7x13x2/2x7x13x5x5=1/5
7 tháng 5 2017
a) \(\frac{21\times11\times2\times17\times4}{11\times17\times21\times3}=\frac{2\times4}{3}_{ }=\frac{8}{3}\)
b)\(\frac{5\times7\times13\times2}{7\times2\times13\times5\times5}=\frac{1}{5}\)
7 tháng 5 2017
a)\(\frac{21x22x68}{11x17x63}\) = \(\frac{1x2x4}{1x1x3}\) =\(\frac{8}{3}\)
b)\(\frac{5x7x26}{14x13x25}\) = \(\frac{1x1x2}{2x1x5}\) =\(\frac{1x1x1}{1x1x5}\) = \(\frac{1}{5}\)
RS
6
a)\(\frac{21}{11}x\frac{22}{17}x\frac{68}{63}\)
=\(\frac{21x22x68}{11x17x63}\)
=\(\frac{21x11x2x17x4}{11x17x21x3}\)
=\(\frac{2x4}{3}\)
=\(\frac{8}{3}\)
b)\(\frac{5}{14}x\frac{7}{13}x\frac{26}{25}\)
=\(\frac{5x7x26}{14x13x25}\)