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\(a)\frac{1}{5}\times\frac{1}{2}:\frac{1}{3}=\frac{1}{5}\times\frac{1}{2}\times\frac{3}{1}=\frac{1\times1\times3}{5\times2\times1}=\frac{1\times3}{5\times2}=\frac{3}{10}\)
\(b)\frac{2}{9}:\frac{2}{3}\times\frac{1}{2}=\frac{2}{9}\times\frac{3}{2}\times\frac{1}{2}=\frac{2\times3\times1}{9\times2\times2}=\frac{1\times1\times1}{3\times1\times2}=\frac{1}{6}\)
\(c)\frac{1}{2}\times\frac{1}{3}+\frac{1}{4}=\frac{1}{6}+\frac{1}{4}=\frac{2}{12}+\frac{3}{12}=\frac{2+3}{12}=\frac{5}{12}\)
d, Tương tự như câu c
P/S : Bất phương trình????
= mười ko ha ngoc chi
mình trả lời mấy lần nhưng toàn hiên ra = 1 thôi à
\(1235\text{×}6789\text{×}\left(630-315\text{×}2\right)\)
\(=1235\text{×}6789\text{×}\left(630-630\right)\)
\(=1235\text{×}6789\text{×}0=0\)
\(\left(100+67\right)\text{×}67+\left(200-38\right)\text{×}33\)
\(=167\text{×}67+167\text{×}33\)
\(=167\text{×}\left(67+33\right)\)
\(=167\text{×}100=16700\)
\(72+36\text{×}2+24\text{×}3+18\text{×}4+12\text{×}2+168\)
\(=72+72+72+72+24+168\)
\(=\left(72\text{×}4\right)+24+168=288+24+168=480\)
3/3x6 + 3/6x9 + 3/9x12 + 3/12x15 + 3/15x18
= 1/3 - 1/6 + 1/6 - 1/9 + ... + 1/15 - 1/18
= 1/3 - 1/18
= 5/18
\(\frac{3}{3\times6}+\frac{3}{6\times9}+\frac{3}{9\times12}+\frac{3}{12\times15}+\frac{3}{15\times18}\)
=\(3\times\left(\frac{1}{3\times6}+\frac{1}{6\times9}+\frac{1}{9\times12}+\frac{1}{12\times15}+\frac{1}{15\times18}\right)\)
=\(3\times\left(\frac{1}{3}\times\frac{1}{6}+\frac{1}{6}\times\frac{1}{9}+\frac{1}{9}\times\frac{1}{12}+\frac{1}{12}\times\frac{1}{15}+\frac{1}{15}\times\frac{1}{18}\right)\)
=\(3\times\left(\frac{1}{3}\times\frac{1}{18}\right)\)
=\(3\times\frac{1}{54}=\frac{3}{54}=\frac{1}{18}\)
\(\frac{3}{7}x\frac{16}{33}+\frac{16}{33}x\frac{4}{7}\)
\(C1:=\frac{16}{77}+\frac{64}{231}=\frac{16}{33}\)
\(C2:=\frac{16}{33}\left(\frac{3}{7}+\frac{4}{7}\right)=\frac{16}{33}.1=\frac{16}{33}\)
học tốt ~~~
C1:3/7×16/33+16/33×4/7
=48/231+64/231
=112/231
C2:3/7×16/33+16/33×4/7
=16/33×(3/7+4/7)
=16/33×7/7
=113/231
3/7x7/3=1
3/7:7/3=1
2/3x1/6x9/11=2/3/54/11=36/11
2x3x4 trên 2x3x4x5=1/5
mk chắc chắn, cho mk nha, kb nhé
\(\frac{3}{7}x\frac{7}{3}=1\)
\(\frac{3}{7}:\frac{7}{3}=1\)
\(\frac{2}{3}x\frac{1}{6}x\frac{9}{11}=\frac{2x1x9}{3x6x11}=\frac{18}{198}=\frac{1}{11}\)
\(\frac{2x3x4}{2x3x4x5}=\frac{1}{5}\)