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\(\frac{5}{15}+\frac{3}{12}+\frac{4}{20}+\frac{18}{27}+\frac{12}{16}+\frac{30}{25}\)
\(=\frac{1}{3}+\frac{1}{4}+\frac{1}{5}+\frac{2}{3}+\frac{3}{4}+\frac{4}{5}\)
\(=\left(\frac{1}{3}+\frac{2}{3}\right)+\left(\frac{1}{4}+\frac{3}{4}\right)+\left(\frac{1}{5}+\frac{4}{5}\right)\)
\(=1+1+1\)
\(=3\)
=(1/11 + 4/11) + (3/4 + 1/4)
=5/11 + 4/4
=5/11+1
=5/11+ 11/11
=16/11
\(\frac{1}{11}+\frac{3}{4}+\frac{4}{11}+\frac{1}{4}\)
\(=\left(\frac{1}{11}+\frac{4}{11}\right)+\left(\frac{3}{4}+\frac{1}{4}\right)\)
\(=\frac{5}{11}+1\)
\(=1\frac{5}{11}\)
\(\frac{2}{3}\cdot\frac{4}{7}+\frac{2}{3}\cdot\frac{3}{7}\)
=\(\frac{2}{3}\left(\frac{4}{7}+\frac{3}{7}\right)\)
= \(\frac{2}{3}\cdot1\)
= \(\frac{2}{3}\)
\(\frac{21}{11}.\frac{22}{17}.\frac{68}{63}=\frac{21.22.68}{11.17.63}=\frac{21.11.2.4.17}{11.17.3.21}=\frac{\left(21.11.17\right).\left(2.4\right)}{\left(11.17.21\right).3}=\frac{2.4}{3}=\frac{8}{3}\)
\(\frac{5}{14}.\frac{7}{13}.\frac{26}{25}=\frac{5.7.26}{14.13.25}=\frac{5.7.13.2}{7.2.13.5.5}=\frac{5.7.13.2}{5.7.13.2.5}=\frac{2}{2.5}=\frac{1}{5}\)
a) 4,56 ; 4,65 ; 6,54 ; 6,45 ; 5,46 ; 5,64
b) tổng các số đó là :
4,56 + 4,65 + 6,54 + 6,45 + 5,46 + 5,64
= ( 4,56 + 5,64 ) + ( 4,65 + 6,45 ) + ( 6,54 + 5,46 )
= 10 + 11,1 + 12
= 33,1
5/12 x 2/3 + 2/3 x 7/12 + 1/3
= 2/3 x ( 5/12 + 7/12 ) + 1/3
= 2/3 x 1 + 1/3
= 2/3 + 1/3
= 1
5/12x2/3+2/3x7/12+1/3
=2/3x(5/12+7/12)+1/3
=2/3x1+1/3
=2/3+1/3
=1
k tui nha @@@