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\(\dfrac{7}{5}+\dfrac{4}{7}-\dfrac{9}{10}=\dfrac{49-20}{35}-\dfrac{9}{10}=\dfrac{19}{35}-\dfrac{9}{10}=\dfrac{190-315}{350}=\dfrac{-125}{350}\)
\(\dfrac{2}{1}+\dfrac{3}{4}\text{×}\dfrac{8}{5}=\dfrac{8+3}{4}\text{×}\dfrac{8}{5}=\dfrac{11\text{×}8}{4\text{×}5}=\dfrac{88}{20}\)
mấy câu kia áp dụng là dc!
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1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10=55
2 + 4 + 6 + 8 + 10 + 12 + 14 + 16 + 18 + 20=110
1 + 3 + 5 + 7 + 9 + 11 + 13 + 15 + 17 + 19=100
k mk nha pạn hiền!
10 +1 = 11 có 10 số vậy thì 10 : 2 = 5 thì sẽ bằng 5x11 = 55
2 + 20 = 22 cũng có 10 số lấy 10 : 2 = 5 se bang 22 x5 = 110
1+19 = 20 , 10 : 2 = 5 , 20x5 = 100
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1+1+2+2+3+3+4+4+5+5+6+6+7+7+8+9+8+9+10+12+13+14+15+16+17+18+19+20+30+1000000=10000274
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\(\dfrac{8}{9}:\dfrac{3}{7}=\dfrac{56}{27}\\ \dfrac{8}{9}+\dfrac{2}{5}=\dfrac{58}{45}\\ \dfrac{7}{8}-\dfrac{1}{3}=\dfrac{13}{24}\\ \dfrac{3}{10}\times\dfrac{1}{6}=\dfrac{1}{20}\\ 1\dfrac{2}{7}+6\dfrac{5}{6}=\dfrac{9}{7}+\dfrac{41}{6}=\dfrac{341}{42}\\ 5\dfrac{3}{4}-\dfrac{1}{5}=\dfrac{23}{4}-\dfrac{1}{5}=\dfrac{111}{20}\\ 6\dfrac{2}{9}:4\dfrac{7}{10}=\dfrac{56}{9}:\dfrac{47}{10}=\dfrac{560}{423}\\ \dfrac{5}{3}+\dfrac{3}{2}-\dfrac{7}{6}=2\)
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\(1,\\ \dfrac{3}{5}=\dfrac{21}{35};\dfrac{4}{7}=\dfrac{20}{35}\\ \dfrac{2}{3}=\dfrac{4}{6};\dfrac{5}{6}=\dfrac{5}{6}\\ \dfrac{4}{9}=\dfrac{8}{18};\dfrac{1}{6}=\dfrac{3}{18}\\ 2,\\ \dfrac{5}{9}=\dfrac{10}{18};\dfrac{7}{8}=\dfrac{14}{16};\dfrac{24}{42}=\dfrac{12}{21}\)
1. \(\dfrac{3}{5}=\dfrac{21}{35};\dfrac{4}{7}=\dfrac{20}{35}\)
\(\dfrac{2}{3}=\dfrac{4}{6};\dfrac{5}{6}=\dfrac{5}{6}\)
\(\dfrac{4}{9}=\dfrac{16}{36};\dfrac{1}{6}=\dfrac{6}{36}\)
2. \(\dfrac{5}{9}=\dfrac{10}{18}\)
\(\dfrac{7}{8}=\dfrac{14}{16}\)
\(\dfrac{24}{42}=\dfrac{12}{21}\)
Ta có : ( 8 x 7 - 16 - 5x 8 ) x ( 1+ 2+3+4+5+6+7+8+9)
= ( 56 - 16 - 40 ) x ( 1+2+3+4+5+6+7+8+9 )
= ( 40 - 40 ) x ( 1+2+3+4+5+6+7+8+9 )
= 0 x ( 1+2+3+4+5+6+7+8+9 )
= 0