5/7 + 1/2 : 2/3 - 9/14 =
( mau lên nhé )
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a, 13/6+5/8 : -3/4 - 7/12.4
= 13/6 + -5/6-7/3
=8/6-7/3
= -6/6
= -1
b, ( 73/5 - 21/3) + ( 4/3-43/5 )
= 73/5-21/3+4/3-43/5
=( 73/5-43/5)-(21/3-4/3)
= 6-17/3
=1/3
c, 7/5.4/9 +7/5: 9/16- 14/10.2/9
= 7/5.4/9 +7/5.16/9 - 14/45
=7/5.(4/9+16/9)-14/45
=7/5.20/9-14/45
= 140/45 - 14/45
= 126/45
Xong rùi nè! Nhưng bạn kiểm tra lại giùm nhé vì làm vào ban đêm nên hơi bất tiện
a: \(\dfrac{x}{0.9}=\dfrac{5}{6}\)
\(\Leftrightarrow x=\dfrac{3}{4}\)
b: \(\dfrac{-6}{x}=\dfrac{9}{-15}\)
\(\Leftrightarrow x=10\)
c: \(\dfrac{\dfrac{14}{15}}{\dfrac{9}{10}}=\dfrac{x}{\dfrac{3}{7}}\)
\(\Leftrightarrow x=\dfrac{3}{7}\cdot\dfrac{14}{15}:\dfrac{9}{10}=\dfrac{2}{5}\cdot\dfrac{10}{9}=\dfrac{20}{45}=\dfrac{4}{9}\)
\(\frac{6}{25}:\frac{21}{20}=\frac{6}{25}.\frac{20}{21}=\frac{6.20}{25.21}=\frac{2.3.4.5}{5.5.3.7}=\frac{8}{35}\)
\(\frac{40}{7}.\frac{14}{5}=\frac{40.14}{7.5}=\frac{8.5.2.7}{7.5}=\frac{16}{1}=16\)
\(\frac{17}{13}:\frac{51}{26}=\frac{17}{13}.\frac{26}{51}=\frac{17.26}{13.51}=\frac{17.2.13}{13.3.17}=\frac{2}{3}\)
Các dấu . là các dấu nhân nha
= (11+19)+(12+18)+(13+17)+(14+16)+15
=(30+30+30+30)+15
=120+15
=135
\(\frac{3^2}{5\cdot14}+\frac{3^2}{7\cdot18}+\frac{3^2}{9.22}+\frac{3^2}{11\cdot26}+\frac{3^2}{13\cdot30}\)
\(=3^2\cdot\left(\frac{1}{5\cdot14}+\frac{1}{7\cdot18}+\frac{1}{9\cdot22}+\frac{1}{11\cdot26}+\frac{1}{13\cdot30}\right)\)
\(=9\cdot\frac{1}{2}\cdot\left(\frac{1}{5\cdot7}+\frac{1}{7\cdot9}+\frac{1}{9\cdot11}+\frac{1}{11\cdot13}+\frac{1}{13\cdot15}\right)\)
\(=\frac{9}{2}\cdot\frac{1}{2}\cdot\left(\frac{2}{5\cdot7}+\frac{2}{7\cdot9}+\frac{2}{9\cdot11}+\frac{2}{11\cdot13}+\frac{2}{13\cdot15}\right)\)
\(=\frac{9}{4}\cdot\left(\frac{1}{5}-\frac{1}{7}+\frac{1}{7}-\frac{1}{9}+\frac{1}{9}-\frac{1}{11}+\frac{1}{11}-\frac{1}{13}+\frac{1}{13}-\frac{1}{15}\right)\)
\(=\frac{9}{4}\cdot\left(\frac{1}{5}-\frac{1}{15}\right)\)
\(=\frac{9}{4}\cdot\frac{2}{15}\)
\(=\frac{3}{10}\)
5/7+1/2:2/3-9/14=5/7+3/4-9/14=20/28+21/28-18/28=23/28
5/7 +1/2 :2/3 -9/14
5/7 + 3/4 - 9/14
23/14