Tìm x :
1/30 : x : 10/15 = 4 * 1/5
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LM
Lê Minh Vũ
CTVHS
15 tháng 6 2023
3 x 15 + 21 x 15 + 85 x 5
= 45 + 315 + 425
= 785
15 - 30 + 40
= 25
21 + 19 - 50 + 10
= 0
\(\dfrac{1}{5}-\dfrac{1}{4}+2\)
\(=-\dfrac{1}{20}+2\)
\(=\dfrac{39}{20}\)
\(\left(\dfrac{1}{4}+\dfrac{1}{6}\right)\times\left(\dfrac{1}{2}-\dfrac{1}{4}\right)\)
\(=\dfrac{5}{12}\times\dfrac{1}{4}\)
\(=\dfrac{5}{12}\times\dfrac{3}{12}\)
\(=\dfrac{5}{48}\)
\(\dfrac{1}{10}+\dfrac{1}{5}-\dfrac{3}{4}\)
\(=-\dfrac{9}{20}\)
BD
15 tháng 6 2023
\(3\times15+21\times15+85\times5\\ =15\times\left(3+21\right)+425\\ =15\times24+425\\ =360+425\\ =785\)
\(15-30+40\\ =\left(15+40\right)-30\\ =55-30\\ =25\)
\(21+19-50+10\\ =\left(21+19\right)-\left(50-10\right)\\ =40-40\\ =0\)
\(\dfrac{1}{5}-\dfrac{1}{4}+2\)
\(=\dfrac{4}{20}-\dfrac{5}{20}+\dfrac{40}{20}\)
\(=\dfrac{\left(4+40\right)}{20}-\dfrac{5}{20}\)
\(=\dfrac{44}{20}-\dfrac{5}{20}\)
\(=\dfrac{39}{20}\)
\(\left(\dfrac{1}{4}+\dfrac{1}{6}\right)\times\left(\dfrac{1}{2}-\dfrac{1}{4}\right)\)
\(=\dfrac{5}{12}\times\dfrac{1}{4}\)
\(=\dfrac{5}{48}\)
\(\dfrac{1}{10}+\dfrac{1}{5}-\dfrac{3}{4}\)
\(=\dfrac{2}{20}+\dfrac{4}{20}-\dfrac{15}{20}\)
\(=\dfrac{6}{20}-\dfrac{15}{20}\)
\(=-\dfrac{9}{20}\)
PA
7 tháng 1 2019
1) 14x-8x=10+5
x(14-8)=15
x6=15
x=15/6
2)5x-3x=30-15
2x=15
x=15/2
3)làm tương tự
12 tháng 3 2022
a)4/5+x=2/3
x=2/3-4/5
x=-2/15
b)-5/6-x=2/3
x=-5/6-2/3
x=-3/2
c)1/2x+3/4=-3/10
1/2x=-3/10-3/4
1/2x=-21/20
x=-21/20:1/2
x=-21/10
d)x/3-1/2=1/5
x/3=1/5+1/2
x/3=7/10
10x/30=21/30
10x=21
x=21:10
x=21/10
12 tháng 7 2021
a) Ta có: \(\left(x-1\right)^{x+2}-\left(x-1\right)^{x+4}=0\)
\(\Leftrightarrow\left(x-1\right)^x\cdot\left(x-1\right)^2-\left(x-1\right)^x\cdot\left(x-1\right)^4=0\)
\(\Leftrightarrow\left(x-1\right)^{x+2}\cdot\left[1-\left(x-1\right)^2\right]=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x-1=0\\x-1=1\\x-1=-1\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=1\\x=2\\x=0\end{matrix}\right.\)
b) Ta có: \(\dfrac{1}{4}\cdot\dfrac{2}{6}\cdot\dfrac{3}{8}\cdot\dfrac{4}{10}\cdot\dfrac{5}{15}\cdot...\cdot\dfrac{30}{62}\cdot\dfrac{31}{64}=2x\)
\(\Leftrightarrow2x=\dfrac{1}{64}\)
hay \(x=\dfrac{1}{128}\)
19 tháng 1 2022
a, thiếu đề
b, -5 ( 2 - x ) + 4 ( x - 3 ) = 10x - 15
<=> -10 + 5x + 4x - 12 = 10x - 15
<=> -x = 7 <=> x = 7
c,-7(5-x)-2(x-10)=15
<=> -35 + 7x - 2x + 20 = 15 <=> 5x = 30 <=> x = 6
d, -4(x+1) + 89x - 3 = 24
<=> 85x = 31 <=> x = 31/85
e, 5(x-30-2(x+6)) = 9
<=> 5 (-x-49) = 9 <=> -5x = 254 <=> x = -254/5
19 tháng 1 2022
b: =>-10+5x+4x-12=10x-15
=>9x-10x=-15+22
=>-x=7
hay x=-7
c: =>-35+7x-2x+20=15
=>5x-15=15
=>x=6
d: =>-4x-4+72x-24=24
=>68x-32=24
hay x=14/17
2 tháng 9 2016
a, (10/3:x).(-5/4)=-10/3
10/3:x=-10/3:(-5/4)
10/3:x=8/3
x=10/3:8/3
x=5/4
b,(-6/5+x):(-18/5)=-1/4
-6/5+x=-1/4.(-18/5)
-6/5+x=9/10
x=9/10-(-6/5)=9/10+6/5
x=21/10
c,-22/15.x+1/3=-2/5
-22/15.x=-2/5-1/3=-11/15
x=-11/15:(-22/15)
x=11/21
d,(0,25-30%x).1/3=-31/6+1/4=-59/12
1/4-3/10x=-59/12:1/3=-59/4
3/10x=1/4-(-59/4)=1/4+59/4=15
x=15:3/10
x=50
e,(0,5x-3/7):1/2=8/7
1/2x=8/7.1/2=4/7
x=4/7:1/2
x=8/7
\(\frac{1}{30}:x:\frac{10}{15}=4\times\frac{1}{5}\)
\(\Rightarrow\frac{1}{30}:x:\frac{2}{3}=\frac{4}{5}\)
\(\Rightarrow\frac{1}{30}:x=\frac{2}{3}\times\frac{4}{5}\)
\(\Rightarrow\frac{1}{30}:x=\frac{8}{15}\)
\(\Rightarrow x=\frac{1}{30}::\frac{8}{15}\)
\(\Rightarrow x=\frac{1}{16}\)
\(\frac{1}{30}:x:\frac{10}{15}=4\cdot\frac{1}{5}\)
\(\frac{1}{30}:x:\frac{2}{3}=\frac{4}{5}\)
\(\frac{1}{30}:x=\frac{4}{5}\cdot\frac{2}{3}\)
\(\frac{1}{30}:x=\frac{8}{15}\)
\(x=\frac{1}{30}:\frac{8}{15}\)
\(x=\frac{1}{16}\)
Vậy X=\(\frac{1}{16}\)