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29 tháng 5 2019
\(\frac{2}{5}.\frac{1}{x}+\frac{1}{x}.2+\frac{2}{5}=0,5\)
\(\Rightarrow\frac{2}{5x}+\frac{2}{x}+\frac{2}{5}=\frac{1}{2}\)
\(\Rightarrow2.\left(\frac{1}{5x}+\frac{1}{x}+\frac{1}{5}\right)=\frac{1}{2}\)
\(\Rightarrow\frac{1}{5x}+\frac{5}{5x}+\frac{x}{5x}=\frac{1}{2}:2=\frac{1}{4}\)
\(\Rightarrow\frac{1+5+x}{5x}=\frac{1}{4}\)
\(\Rightarrow4.\left(1+5+x\right)=5x\)
\(\Rightarrow4+20+4x=5x\)
\(\Rightarrow24+4x=5x\)
\(\Rightarrow5x-4x=24\)
\(\Rightarrow x=24\)
CN
23 tháng 7 2018
1.\(\dfrac{-1}{4}\) \(-\) x \(=\dfrac{-3}{2}\)
\(\Leftrightarrow\) x \(\dfrac{-3}{2}-\dfrac{-1}{4}\)
\(\Leftrightarrow\) x \(=\dfrac{-5}{4}\)
24 tháng 7 2018
1. -1/4 - x = -3/2
x = -1/4 - -3/2
x = -1/4 - -6/4
x = 5/4
2. 3/5 . (x - 1/2) : 3/5 - 1/3 = -1/2
3/5 . (x - 1/2) : 3/5 = -1/2 + 1/3
3/5 . (x - 1/2) : 3/5 = -3/6 + 2/6
3/5 . (x - 1/2) : 3/5 = -1/6
3/5 . (x - 1/2) = -1/6 . 3/5
3/5 . (x - 1/2) = -1/10
x - 1/2 = -1/10 : 3/5
x - 1/2 = -1/6
x = -1/6 + 1/2
x = -1/6 + 3/6
x = 2/6
x = 1/3
Mấy câu sau bn tự làm nha!
T
7 tháng 10 2023
Bài 1.
\(a,\left(2^4\cdot3\cdot5^2\right):\left\{450:\left[450-\left(4\cdot5^3-2^3\cdot5^2\right)\right]\right\}\)
\(=\left(16\cdot3\cdot25\right):\left\{450:\left[450- \left(4\cdot125-8\cdot25\right)\right]\right\}\)
\(=\left(48\cdot25\right):\left\{450:\left[450-\left(500-200\right)\right]\right\}\)
\(=1200:\left[450:\left(450-300\right)\right]\)
\(=1200:\left(450:150\right)\)
\(=1200:3\)
\(=400\)
\(---\)
\(b,3^3\cdot5^2-20\left\{90-\left[164-2\cdot\left(7^8:7^6+7^0\right)\right]\right\}\)
\(=27\cdot25-20\left\{90-\left[164-2\cdot\left(7^2+1\right)\right]\right\}\)
\(=675-20\left\{90-\left[164-2\cdot\left(49+1\right)\right]\right\}\)
\(=675-20\left[90-\left(164-2\cdot50\right)\right]\)
\(=675-20\left[90-\left(164-100\right)\right]\)
\(=675-20\left(90-64\right)\)
\(=675-20\cdot26\)
\(=675-520\)
\(=155\)
\(---\)
\(c,\left[\left(18^7:18^6-17\right)\cdot2022-1986\right]\cdot5\cdot1^{2022}-13^2\cdot2020^0\)
\(=\left[\left(18-17\right)\cdot2022-1986\right]\cdot5\cdot1-169\cdot1\)
\(=\left(1\cdot2022-1986\right)\cdot5-169\)
\(=\left(2022-1986\right)\cdot5-169\)
\(=36\cdot5-169\)
\(=180-169\)
\(=11\)
Bài 2.
\(a) (2^x+1)^2+3\cdot(2^2+1)=2^2\cdot10\\\Rightarrow (2^x+1)^2+3\cdot(4+1)=4\cdot10\\\Rightarrow (2^x+1)^2+3\cdot5=40\\\Rightarrow (2^x+1)^2+15=40\\\Rightarrow (2^x+1)^2=40-15\\\Rightarrow (2^x+1)^2=25\\\Rightarrow (2^x+1)^2= (\pm 5)^2\\\Rightarrow \left[\begin{array}{} 2^x+1=5\\ 2^x+1=-5 \end{array} \right.\\ \Rightarrow \left[\begin{array}{} 2^x=4\\ 2^x=-6 (vô.lí) \end{array} \right. \\ \Rightarrow 2^x=2^2\\\Rightarrow x=2\)
Vậy \(x=2\).
\(---\)
\(b)3\cdot(x-7)+2\cdot(x+5)=41\\\Rightarrow 3\cdot x+3\cdot(-7)+2\cdot x+2\cdot5=41\\\Rightarrow 3x-21+2x+10=41\\\Rightarrow (3x+2x)+(-21+10)=41\\\Rightarrow 5x-11=41\\\Rightarrow 5x=41+11\\\Rightarrow 5x=52\\\Rightarrow x=\dfrac{52}{5}\)
Vậy \(x=\dfrac{52}{5}\).
\(Toru\)
KN
14 tháng 4 2016
2/5.1/3-2/15:1/5+3/5.1/3
= ( 2/5 . 1/3 ) - ( 2/15 : 1/5 ) + (3/5 . 1/3 )
= 2/15 - 2/75 + 1/5
= 23/75
\(\frac{1}{5}.\frac{1}{x}+\frac{1}{5}.\frac{1}{x}=\frac{1}{2}\)
<=> \(2.\frac{1}{5}.\frac{1}{x}=\frac{1}{2}\)
<=> \(\frac{1}{x}=\frac{5}{4}\)
<=> x = 0,8
miku ơi bạn làm sai rồi
mình biết cách làm rồi
x=4