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42.120-43.17+42.34
=42.120-42.4.17+42.34
=42.120-42.68+42.34
=42.(120-68+34)
=16.86
=1376
=42.120-42.41.17+42.34
=42.120-42.68+42.34
=42.(120-68+34)
=16.86
1376
Dấu chấm là nhân đấy các bạn "..''
A=-4/5+4/3+-5/4+14/5-7/3
A=(-4/5+14/5)+(4/3-7/3)+-5/4
A=2+-1+-5/4
A=1-5/4
A=-1/4
\(\frac{12-\frac{12}{7}-\frac{12}{289}-\frac{12}{85}}{4-\frac{4}{7}-\frac{4}{289}-\frac{4}{85}}:\frac{3+\frac{3}{13}+\frac{3}{169}+\frac{3}{91}}{7+\frac{7}{13}+\frac{7}{169}+\frac{7}{91}}\)\(=\frac{12.\left(1-\frac{1}{7}-\frac{1}{289}-\frac{1}{85}\right)}{4.\left(1-\frac{1}{7}-\frac{1}{289}-\frac{1}{85}\right)}:\frac{3.\left(1+\frac{1}{13}+\frac{1}{169}+\frac{1}{91}\right)}{7.\left(1+\frac{1}{13}+\frac{1}{169}+\frac{1}{91}\right)}\)
\(=\frac{12}{4}:\frac{3}{7}\)
\(=3.\frac{7}{3}=7\)
\(\frac{12-\frac{12}{7}-\frac{12}{289}-\frac{12}{85}}{4-\frac{4}{7}-\frac{4}{289}-\frac{4}{85}}:\frac{3+\frac{3}{13}+\frac{3}{169}+\frac{3}{91}}{7+\frac{7}{13}+\frac{7}{169}+\frac{7}{91}}\)
\(=\frac{12\left(1-\frac{1}{7}-\frac{1}{289}-\frac{1}{85}\right)}{4\left(1-\frac{1}{7}-\frac{1}{289}-\frac{1}{85}\right)}:\frac{3\left(1+\frac{1}{13}+\frac{1}{169}+\frac{1}{9}\right)}{7\left(1+\frac{1}{13}+\frac{1}{169}+\frac{1}{9}\right)}\)
\(=3:\frac{3}{7}\)
\(=7\)
\(a)\left(6\frac{4}{11}+3\frac{7}{9}\right)-4\frac{4}{11}\)
\(=(6\frac{4}{11}-4\frac{4}{11})+3\frac{7}{9}\)
\(=2\frac{4}{11}+3\frac{7}{9}\)
\(=\frac{26}{11}+\frac{34}{9}\)
\(=\frac{608}{99}\)
\(11\frac{3}{13}-\left(2\frac{4}{7}+5\frac{3}{13}\right)\)
\(=11\frac{3}{13}-2\frac{4}{7}-5\frac{3}{13}\)
\(=11+\frac{3}{13}-2-\frac{4}{7}-5-\frac{3}{13}\)
\(=\left(11-2-5\right)+\left(\frac{3}{13}-\frac{3}{13}\right)-\frac{4}{7}\)
\(=4+\frac{4}{7}\)
\(=4\frac{4}{7}\)
hok tốt
\(11\frac{3}{13}-\left(1\frac{4}{7}+5\frac{3}{13}\right)\)
\(=\frac{146}{13}-\left(\frac{11}{7}+\frac{68}{13}\right)\)
\(=\left(\frac{146}{13}-\frac{68}{13}\right)+\frac{11}{7}\)
\(=6+\frac{11}{7}\)
\(=\frac{53}{7}\)
Học tốt #
\(B=\frac{4}{35}+\frac{4}{63}+\frac{4}{99}+\frac{4}{143}+\frac{4}{195}\)
\(B=2\cdot\left(\frac{2}{5\cdot7}+\frac{2}{7\cdot9}+\frac{2}{9\cdot11}+\frac{2}{11\cdot13}+\frac{2}{13\cdot15}\right)\)
\(B=2\cdot\left(\frac{1}{5}-\frac{1}{7}+\frac{1}{7}-\frac{1}{9}+\frac{1}{9}-\frac{1}{11}+\frac{1}{11}-\frac{1}{13}+\frac{1}{13}-\frac{1}{15}\right)\)
\(B=2\cdot\left(\frac{1}{5}-\frac{1}{15}\right)\)
\(B=2\cdot\frac{2}{15}\)
\(B=\frac{4}{15}\)
B = 4/35 + 4/63 + 4/99 + 4/143 + 4/195
B = 4/5.7 + 4/7.9 + 4/9.11 + 4/11.13 + 4/13.15
B = 4/2 . ( 2/5.7 + 2/7.9 + 2/9.11 + 2/11.13 + 2/13.15 )
B = 4/2 . ( 1/5 - 1/7 + 1/7 - 1/9 + 1/9 - 1/11 + 1/11 - 1/13 + 1/13 - 1/15 )
B = 4/2 . ( 1/5 - 1/15 )
B = 4/2 . 2/15
B = 4/15
4^2.102-4^2.4.17-4^2.34=4^2.(102-4.17-34)=16.(102-68-34)=16.0=0
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