Tính giá trị của biểu thức
1 2 × 1 3 + 1 4 4 7 : 2 3 - 3 7
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\(\dfrac{1}{2}\times\dfrac{1}{3}+\dfrac{3}{4}\)
\(=\dfrac{1}{6}+\dfrac{3}{4}\)
\(=\dfrac{2}{12}+\dfrac{9}{12}\)
\(=\dfrac{11}{12}\)
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\(\dfrac{3}{7}-\dfrac{2}{7}:\dfrac{2}{3}\)
\(=\dfrac{3}{7}-\dfrac{2}{7}\times\dfrac{3}{2}\)
\(=\dfrac{3}{7}-\dfrac{3}{7}\)
\(=0\)
Chúc bạn học tốt
1/2 x 1/3 + 3/4 = 1/6 + 3/4 = 4/24 + 18/24 = 22/24 = 11/12
3/7 - 2/7 : 2/3 = 3/7 - 2/7 x 3/2 = 3/7 - 3/7 = 0
a: \(x:5=\dfrac{15}{14}\\ \Rightarrow x=\dfrac{15}{70}=\dfrac{3}{14}\)
a)
\(\begin{array}{l}A = \left( {2 + \frac{1}{3} - \frac{2}{5}} \right) - \left( {7 - \frac{3}{5} - \frac{4}{3}} \right) - \left( {\frac{1}{5} + \frac{5}{3} - 4} \right).\\A = \left( {\frac{{30}}{{15}} + \frac{5}{{15}} - \frac{6}{{15}}} \right) - \left( {\frac{{105}}{{15}} - \frac{9}{{15}} - \frac{{20}}{{15}}} \right) - \left( {\frac{3}{{15}} + \frac{{25}}{{15}} - \frac{{60}}{{15}}} \right)\\A = \frac{{29}}{{15}} - \frac{{76}}{{15}} - \left( {\frac{{ - 32}}{{15}}} \right)\\A = \frac{{29}}{{15}} - \frac{{76}}{{15}} + \frac{{32}}{{15}}\\A = \frac{{ - 15}}{{15}}\\A = - 1\end{array}\)
b)
\(\begin{array}{l}A = \left( {2 + \frac{1}{3} - \frac{2}{5}} \right) - \left( {7 - \frac{3}{5} - \frac{4}{3}} \right) - \left( {\frac{1}{5} + \frac{5}{3} - 4} \right)\\A = 2 + \frac{1}{3} - \frac{2}{5} - 7 + \frac{3}{5} + \frac{4}{3} - \frac{1}{5} - \frac{5}{3} + 4\\A = \left( {2 - 7 + 4} \right) + \left( {\frac{1}{3} + \frac{4}{3} - \frac{5}{3}} \right) + \left( { - \frac{2}{5} + \frac{3}{5} - \frac{1}{5}} \right)\\A = - 1 + 0 + 0 = - 1\end{array}\)
Ta có: \(\left(3\dfrac{3}{4}+\dfrac{4}{7}\cdot\dfrac{7}{16}\right):\dfrac{1}{2}\)
\(=\left(\dfrac{15}{4}+\dfrac{1}{4}\right)\cdot2\)
\(=4\cdot2=8\)
\(\dfrac{1}{3}\cdot\dfrac{1}{4}+\dfrac{7}{4}:3-\dfrac{2}{3}\)
\(=\dfrac{1}{12}+\dfrac{7}{12}-\dfrac{8}{12}\)
\(=\dfrac{0}{12}=0\)
`a, 3/4 + 1/2 xx 7/2`
`= 3/4 + 7/4`
`=10/4`
`=5/2`
`b, 6/15 - 1/3 : 5/3`
`= 6/15 - 1/3 xx 3/5`
`= 6/15 - 3/15`
`= 3/15`
`=1/5`
`c, x-4/9 = 3/7 : 9/4`
`=> x-4/9= 3/7 xx 4/9`
`=> x-4/9= 12/63`
`=> x-4/9=4/21`
`=> x= 4/21 +4/9`
`=>x= 40/63`
`d, 7/9 xx 3/5 -1/2=1/5`
`->` sao lại bằng có `x` ko vậy ạ?
`a,`
`3/4+1/2 \times 7/2=3/4+7/4=10/4=5/2`
`b,`
`6/15 - 1/3 \div 5/3=6/15-1/5=1/5`
`c,` Tìm x?
`x-4/9=3/7 \div 9/4`
`x-4/9=4/21`
`x=4/21+4/9`
`x=40/63`
`d, 7/9x \times 3/5-1/2=1/5`
`7/9x \times 3/5=1/5+1/2`
`7/9x \times 3/5=7/10`
`7/9x=7/10 \div 3/5`
`7/9x=7/6`
`x=7/6 \div 7/9=3/2`