tìm x biết (7/3.x-0,6):3 2/5=1
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a) \(2\frac{1}{2}-\left(q-\frac{1}{2}\right)=\frac{3}{5}\)
\(\Rightarrow q-\frac{1}{2}=2\frac{1}{2}-\frac{3}{5}=\frac{19}{10}\)
\(\Rightarrow q=\frac{19}{10}+\frac{1}{2}=\frac{12}{5}=2,4\)
\(\Rightarrow q=2,4\)
b) \(\frac{1}{3}\cdot q-\frac{1}{5}\cdot q=0,6\)
\(=q\cdot\left(\frac{1}{3}-\frac{1}{5}\right)=0,6\)
\(=q\cdot\frac{2}{15}=0,6\)
\(\Rightarrow q=0,6:\frac{2}{15}=\frac{9}{2}=4,5\)
\(\Rightarrow q=4,5\)
c) \(\frac{3}{5}-q:\frac{1}{2}=\frac{1}{7}\)
\(\Rightarrow q:\frac{1}{2}=\frac{3}{5}-\frac{1}{7}=\frac{16}{35}\)
\(\Rightarrow q=\frac{16}{35}\cdot\frac{1}{2}=\frac{8}{35}\)
\(\Rightarrow q=\frac{5}{35}\)
Ở câu b áp dụng phân phối giữa phép nhân vs phép trừ.
1) x-2/5=0,24 2) (7/3 . x -0,6) : 3 . 2/5=1
x =6/25+2/5 (7/3 . x -3/5) :3 = 1: 2/5
x =6/25+10/25 (7/3 . x -3/5) :3 = 5/2
x =16/25 7/3 . x -3/5 =5/2 . 3
7/3 . x -3/5 =15/2
7/3 .x =15/2+3/5
7/3. x = 81/10
x = 81/10 : 7/3
x =243/70
2) \(\left(\frac{7}{3}.x-0,6\right):3\frac{2}{5}=1\Rightarrow\left(\frac{7}{3}x-\frac{3}{5}\right):\frac{17}{5}=1\Rightarrow\left(\frac{7}{3}x-\frac{3}{5}\right)=\frac{17}{5}\Rightarrow\frac{7}{3}x=\frac{17}{5}+\frac{3}{5}=4\Rightarrow4:\frac{7}{3}=4.\frac{3}{7}=\frac{12}{7}=1\frac{5}{7}\)
a) \(-0,6x-\dfrac{7}{3}=5,4\Leftrightarrow-\dfrac{3}{5}x=5,4+\dfrac{7}{3}\Leftrightarrow x=\dfrac{116}{15}.\left(-\dfrac{5}{3}\right)=-\dfrac{116}{9}\).
b) \(2,8:\left(\dfrac{1}{5}-3x\right)=1\dfrac{2}{5}\Leftrightarrow\dfrac{1}{5}-3x=2,8:\dfrac{7}{5}\Leftrightarrow-3x=2-\dfrac{1}{5}\Leftrightarrow x=\dfrac{9}{5}:\left(-3\right)=-\dfrac{3}{5}\).
`@` `\text {Ans}`
`\downarrow`
`a,`
`(x-1954) \times 5=50`
`x-1954 = 50 \div 5`
`x-1954 = 10`
`x=10 + 1954`
`x= 1964`
`B.`
`48 - 40 \times x=8`
`40 \times x=48-8`
`40 \times x = 40`
` x=40 \div 40`
`x=1`
`C.`
`2+70 \div x = 3`
`70 \div x = 3-2`
`70 \div x = 1`
`x=70 \div 1`
`x=70`
`D. [3 \times (x+2) \div 7] \times 4=120`
`3 \times (x+2) \div 7 = 120 \div 4`
`3 \times (x+2) \div 7 =30`
`3 \times (x+2) = 30 \times 7`
`3 \times (x+2)=210`
`x+2=210 \div 3`
`x+2=70`
`x=70-2`
`x=68`
`E.`
`7,2 \div [ (0,6 \times x+8) \div 20 + 59] = 0,12?` Thiếu ngoặc bạn nhé._.
\(a,\left(x-1954\right)\times5=50\\ x-1954=50:5\\ x-1954=10\\ x=1954+10\\ x=1964\\b.48-40\times x=8\\40\times x=48-8\\40\times x=40\\ x=40:40\\ x=1 \\ c.2+70:X=3\\ 70:x=3-2\\ 70:x=1\\ x=70:1\\ x=70\\ d,\left[3\times\left(x+2\right):7\right]\times4=120\\ 3\times\left(x+2\right):7-120:4\\ 3\times\left(x+2\right):7=30\\ \left(x+2\right):7=30:3\\ \left(x+2\right):7=10\\ x+2=10\times7\\ x+2=70\\ x=70-2\\ x=68\)
a) -0,6 . x - 7/3 = 5,4 (sửa dấu phẩy thành dấu nhân)
=> \(-\frac{3}{5}x-\frac{7}{3}=\frac{27}{5}\)
=> \(-\frac{3}{5}x=\frac{27}{5}+\frac{7}{3}=\frac{116}{15}\)
=> \(x=\frac{116}{15}:\left(-\frac{3}{5}\right)=\frac{116}{15}\cdot\left(-\frac{5}{3}\right)=-\frac{116}{9}\)
b) 2,8 : \(\left(\frac{1}{5}-3x\right)=1\frac{2}{5}\)
=> \(\frac{1}{5}-3x=2,8:1\frac{2}{5}\)
=> \(\frac{1}{5}-3x=\frac{14}{5}:\frac{7}{5}=\frac{14}{5}\cdot\frac{5}{7}=2\)
=> 3x = \(\frac{1}{5}-2=-\frac{9}{5}\)
=> \(x=\left(-\frac{9}{5}\right):3=\left(-\frac{9}{5}\right)\cdot\frac{1}{3}=-\frac{3}{5}\)
Nên sửa lại đề câu a đi nhá :))