Bài 7: Tính giá trị biểu thức:
a) A=( \(\frac{1}{4}-\frac{1}{4}+\frac{1}{9}:\frac{1}{9}\)) : (\(\frac{2}{3}+\frac{7}{15}:\frac{2}{5}-\frac{1}{6}\))
b) B = (0,8.7+0,64).(1,25.7-\(\frac{4}{6}\).1,25) +31,64
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Bài 7: Tính giá trị biểu thức:
a) A = \(\left(\frac{\frac{1}{4}-\frac{1}{4}+\frac{1}{9}}{\frac{1}{9}}\right):\left(\frac{\frac{2}{3}+\frac{7}{15}}{\frac{2}{5}-\frac{1}{6}}\right)\)
b) B = (0,8.7+0,64).(1,25.7-\(\frac{4}{6}\).1,25) +31,64
a: \(A=\dfrac{1}{9}:\dfrac{1}{9}:\left(\dfrac{10+7}{15}:\dfrac{12-5}{30}\right)\)
\(=1:\left(\dfrac{17}{15}\cdot\dfrac{30}{7}\right)=1:\dfrac{34}{7}=\dfrac{7}{34}\)
b: \(=\left(5.6+0.64\right)\cdot1.25\cdot\dfrac{19}{3}+31.64\)
\(=\dfrac{39}{5}\cdot\dfrac{19}{3}+\dfrac{791}{25}=\dfrac{2026}{25}\)
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Bài 7: Tính giá trị biểu thức:
a) A = \(\left(\frac{\frac{1}{4}-\frac{1}{4}+\frac{1}{9}}{\frac{1}{9}}\right):\left(\frac{\frac{2}{3}+\frac{7}{15}}{\frac{2}{5}-\frac{1}{6}}\right)\)
b) B = (0,8.7+0,64).(1,25.7-4646.1,25) +31,64
Tính giá trị của biểu thức sau: \(M=\frac{-1,2:\left(1\frac{3}{5}.1,25\right)}{0,64-\frac{1}{25}}+\frac{\left(1,08-\frac{2}{25}\right):\frac{4}{7}}{\left(5\frac{5}{9}-\frac{9}{4}\right).\frac{36}{17}+}+0,6.0,5:\frac{2}{3}\)
Rút gọn
1.left(frac{2}{45}-frac{4}{13}-frac{1}{3}right):left(frac{3}{13}-frac{4}{15}+frac{2}{13}right)
2.frac{0,8:left(frac{4}{5}.1,25right)}{0,64-frac{1}{25}}+frac{left(1,08-frac{2}{15}right):frac{4}{7}}{left(6frac{5}{9}-3frac{1}{4}right)2frac{2}{17}}
3.frac{0,4-frac{2}{9}+frac{2}{11}}{1,4-frac{7}{9}+frac{7}{11}}-frac{frac{1}{3}-0,25+frac{1}{5}}{1frac{1}{6}-0,875+0,7}
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Rút gọn
1.\(\left(\frac{2}{45}-\frac{4}{13}-\frac{1}{3}\right):\left(\frac{3}{13}-\frac{4}{15}+\frac{2}{13}\right)\)
2.\(\frac{0,8:\left(\frac{4}{5}.1,25\right)}{0,64-\frac{1}{25}}+\frac{\left(1,08-\frac{2}{15}\right):\frac{4}{7}}{\left(6\frac{5}{9}-3\frac{1}{4}\right)2\frac{2}{17}}\)
3.\(\frac{0,4-\frac{2}{9}+\frac{2}{11}}{1,4-\frac{7}{9}+\frac{7}{11}}-\frac{\frac{1}{3}-0,25+\frac{1}{5}}{1\frac{1}{6}-0,875+0,7}\)
2: \(=\dfrac{0.8}{\dfrac{16}{25}-\dfrac{1}{25}}+\dfrac{\dfrac{71}{75}\cdot\dfrac{7}{4}}{\dfrac{119}{36}\cdot\dfrac{36}{17}}\)
\(=\dfrac{4}{5}\cdot\dfrac{5}{3}+\dfrac{71}{300}=\dfrac{471}{300}=\dfrac{157}{100}\)
3: \(=\dfrac{\dfrac{2}{5}-\dfrac{2}{9}+\dfrac{2}{11}}{\dfrac{7}{5}-\dfrac{7}{9}+\dfrac{7}{11}}-\dfrac{\dfrac{2}{6}-\dfrac{2}{8}+\dfrac{2}{10}}{\dfrac{7}{6}-\dfrac{7}{8}+\dfrac{7}{10}}\)
=2/7-2/7=0
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Thực hiện phép tính một cách hợp lí:
a)\(\frac{0,8:\left(\frac{4}{5}.1,25\right)}{0,64-\frac{1}{25}}+\frac{\left(1,08-\frac{2}{25}\right):\frac{4}{7}}{\left(6\frac{5}{9}-3\frac{1}{4}\right).2\frac{2}{17}}\)
b)\(\frac{0,4-\frac{2}{9}+\frac{2}{11}}{1,4-\frac{7}{9}+\frac{7}{11}}-\frac{\frac{1}{3}-0,25+\frac{1}{5}}{1\frac{1}{6}-0,875+0,7}\)
Giải đầy đủ giúp mk nha, cảm ơn nhìu
Tính nhanh : \(\frac{0,8:\left[\frac{4}{5}.1,25\right]}{0,64-\frac{1}{25}}+\frac{1,08-\frac{2}{25}:\frac{4}{7}}{\left[6\frac{5}{9}-3\frac{1}{4}\right].2\frac{2}{7}}\)
Bài 4 :
a) Tính giá trị của biểu thức :
\(A=\left(\frac{1\frac{11}{31}\cdot4\frac{3}{7}-\left(15-6\frac{1}{3}\cdot\frac{2}{19}\right)}{4\frac{5}{6}+\frac{1}{6}\left(12-5\frac{1}{3}\right)}\cdot\left(-1\frac{14}{93}\right)\right)\cdot\frac{31}{50}\)
b) Chứng tỏ rằng : \(B=1-\frac{1}{2^2}-\frac{1}{3^2}-\frac{1}{3^2}-...-\frac{1}{2004^2}>\frac{1}{2004}\)
Tính hợp lý: \(\frac{0,8:\left[\frac{4}{5}.1,25\right]}{0,64-\frac{1}{25}}+\frac{1,08-\frac{2}{25}:\frac{4}{7}}{\left[6\frac{5}{9}-3\frac{1}{4}\right].2\frac{2}{7}}\)
tính \(\frac{0,8:\left(\frac{4}{5}.1,25\right)}{0,64-\frac{1}{25}}\)+\(\frac{\left(1,08-\frac{2}{5}\right):\frac{4}{7}}{\left(6\frac{5}{9}-3\frac{1}{4}\right).2\frac{2}{17}}\)
đặt
\(M=\frac{0,8:\left(\frac{4}{5}.1,25\right)}{0,64-\frac{1}{25}}=\frac{\frac{4}{5}.1}{\frac{16}{25}-\frac{1}{25}}=\frac{\frac{4}{5}}{\frac{3}{5}}=\frac{4}{3}\)
\(N=\frac{\left(1,08-\frac{2}{25}\right):\frac{4}{7}}{\left(6\frac{5}{9}-3\frac{1}{4}\right).2\frac{2}{17}}=\frac{\left(\frac{27}{25}-\frac{2}{25}\right):\frac{4}{7}}{\left(\frac{59}{9}-\frac{13}{4}\right).\frac{36}{17}}=\frac{1:\frac{4}{7}}{7}=\frac{1}{4}\)
\(=>M+N=\frac{3}{4}+\frac{1}{4}=1\)