Tìm x
(5+4/7):x=13
(2,8.x+32):2/3=90
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16 tháng 7 2021
`a)(4,5-2x)*1 4/7=11/14`
`=>(4,5-2x)*11/7=11/14`
`=>4,5-2x=1/2`
`=>2x=4,5-0,5=4`
`=>x=2`
Vậy `x=2`
`b)(2,8x-32):2/3=-90`
`=>2,8x-32=-90*2/3=-60`
`=>2,8x=-28`
`=>x=-10`
Vậy `x=-10`
DM
1
Q
15 tháng 3 2017
\(\left(2,8:x-32\right):\frac{2}{3}=-90\)
\(2,8:x-32=\left(-90\right).\frac{2}{3}\)
\(2,8:x-32=-60\)
\(2,8:x=-28\)
\(x=\left(-28\right):2,8\)
\(x=-10\)
\(4-\left|x-2012\right|=\left(-2\right)^2\)
\(4-\left|x-2012\right|=-4\)
\(\left|x-2012\right|=8\)
\(\Rightarrow\orbr{\begin{cases}\left|x-2012\right|=8\\\left|x-2012\right|=-8\end{cases}\Rightarrow\orbr{\begin{cases}x=2020\\x=2004\end{cases}}}\)
Q
4 tháng 5 2022
(2,8 . x - 32) : 2/3 = -90
(2,8 . x - 32) = -90 x 2/3
(2,8 . x - 32) = -60
2,8 . x = -60 + 32
2,8 . x = -28
x = -28 : 2,8
x = -10
4 tháng 5 2022
`(2,8 . x - 32) : 2/3 = -90`
`(2,8 . x - 32) = -90 xx (-2/3)`
`2,8 . x = 60 + 32`
`2,8 . x = 92`
`x = 92 : 2,8`
`x = 92/2,8`
DN
12 tháng 7 2016
( 2,8x - 32 ) : 2/3 = -90
2,8x - 32 = -90.2/3
2,8x - 32 = -60
2.8x = -60+32
2.8x = -28
x = -10
F
23 tháng 1 2020
Bài giải
a, \(\frac{4}{5}-\frac{2}{3}+\frac{1}{5}-\frac{1}{3}\)
\(=\left(\frac{4}{5}+\frac{1}{5}\right)-\left(\frac{2}{3}+\frac{1}{3}\right)=1-1=0\)
b, \(\frac{2}{5}\text{ x }\frac{7}{4}-\frac{2}{5}\text{ x }\frac{3}{7}\)
\(=\frac{2}{5}\text{ x }\left(\frac{7}{4}-\frac{3}{7}\right)=\frac{2}{5}\text{ x }\frac{37}{28}=\frac{37}{70}\)
c, \(\frac{13}{4}\text{ x }\frac{2}{3}\text{ x }\frac{4}{13}\text{ x }\frac{3}{12}=\frac{13\text{ x }2\text{ x }4\text{ x }3}{4\text{ x }3\text{ x }13\text{ x }12}=\frac{1}{6}\)
d, \(\frac{75}{100}+\frac{18}{21}+\frac{19}{32}+\frac{1}{4}+\frac{3}{21}+\frac{13}{32}\)
\(=\frac{3}{4}+\frac{18}{21}+\frac{19}{32}+\frac{1}{4}+\frac{3}{21}+\frac{13}{32}\)
\(=\left(\frac{3}{4}+\frac{1}{4}\right)+\left(\frac{18}{21}+\frac{3}{21}\right)+\left(\frac{19}{32}+\frac{13}{32}\right)\)
\(=1+1+1\)
\(=3\)
e, \(\frac{2}{5}+\frac{6}{9}+\frac{3}{4}+\frac{3}{5}+\frac{1}{3}+\frac{1}{4}\)
\(=\frac{2}{5}+\frac{2}{3}+\frac{3}{4}+\frac{3}{5}+\frac{1}{3}+\frac{1}{4}\)
\(=\frac{1}{5}\left(2+3\right)+\frac{1}{3}\left(2+1\right)+\frac{1}{4}\left(3+1\right)\)
\(=\frac{1}{5}\cdot5+\frac{1}{3}\cdot3+\frac{1}{4}\cdot4\)
\(=1+1+1\)
\(=3\)
M
23 tháng 1 2020
a, \(\frac{4}{5}-\frac{2}{3}+\frac{1}{5}-\frac{1}{3}\)
\(=\left(\frac{4}{5}+\frac{1}{5}\right)-\left(\frac{2}{3}+\frac{1}{3}\right)=1-1=0\)
b, \(\frac{2}{5}\text{ x }\frac{7}{4}-\frac{2}{5}\text{ x }\frac{3}{7}\)
\(=\frac{2}{5}\text{ x }\left(\frac{7}{4}-\frac{3}{7}\right)=\frac{2}{5}\text{ x }\frac{37}{28}=\frac{37}{70}\)
c, \(\frac{13}{4}\text{ x }\frac{2}{3}\text{ x }\frac{4}{13}\text{ x }\frac{3}{12}=\frac{13\text{ x }2\text{ x }4\text{ x }3}{4\text{ x }3\text{ x }13\text{ x }12}=\frac{1}{6}\)
d, \(\frac{75}{100}+\frac{18}{21}+\frac{19}{32}+\frac{1}{4}+\frac{3}{21}+\frac{13}{32}\)
\(=\frac{3}{4}+\frac{18}{21}+\frac{19}{32}+\frac{1}{4}+\frac{3}{21}+\frac{13}{32}\)
\(=\left(\frac{3}{4}+\frac{1}{4}\right)+\left(\frac{18}{21}+\frac{3}{21}\right)+\left(\frac{19}{32}+\frac{13}{32}\right)\)
\(=1+1+1\)
\(=3\)
e, \(\frac{2}{5}+\frac{6}{9}+\frac{3}{4}+\frac{3}{5}+\frac{1}{3}+\frac{1}{4}\)
\(=\frac{2}{5}+\frac{2}{3}+\frac{3}{4}+\frac{3}{5}+\frac{1}{3}+\frac{1}{4}\)
\(=\frac{1}{5}\left(2+3\right)+\frac{1}{3}\left(2+1\right)+\frac{1}{4}\left(3+1\right)\)
\(=\frac{1}{5}\cdot5+\frac{1}{3}\cdot3+\frac{1}{4}\cdot4\)
\(=1+1+1\)
\(=3\)
1 tháng 5 2019
\(\frac{a}{27}=\frac{-5}{9}=\frac{-45}{b}\)
\(=>\frac{a.3}{81}=\frac{-45}{81}=\frac{-45}{b}\)
=>b=81
a.3=-45
a=-15
Vậy a=-15;b=81
3 tháng 8 2016
(2,8.x-32):2/3=-90
=>2,8.x-32=90x2/3
=>2,8.x-32=60
=>2,8.x=60+32
=>2,8.x=92
=>x=92:2,8
=>x=230/7
4 tháng 8 2016
( 2,8.x - 32 ) : \(\frac{2}{3}\) = - 90
= 2,8.x - 32 = 90. \(\frac{2}{3}\)
= 2,8.x - 32 = 60
= 2,8.x = 60 + 32
= 2,8.x = 92
x = 92 : 2,8
x = \(\frac{230}{7}\)
Vậy x bằng \(\frac{230}{7}\)
\(\left(5+\frac{4}{7}\right):x=13\)
\(\frac{39}{7}:x=13\)
\(x=\frac{39}{7}:13\)
\(x=\frac{3}{7}\)
\(\left[5+\frac{4}{7}\right]:x=13\)
\(\Rightarrow\left[\frac{5\cdot7+4}{7}\right]:x=13\)
\(\Rightarrow\frac{39}{7}:x=13\)
\(\Rightarrow x=\frac{39}{7}:13=\frac{39}{7}\cdot\frac{1}{13}=\frac{3}{7}\cdot\frac{1}{1}=\frac{3}{7}\)
\(\left[2,8\cdot x+32\right]:\frac{2}{3}=90\)
\(\Rightarrow\left[2,8\cdot x+32\right]=90\cdot\frac{2}{3}\)
\(\Rightarrow\left[2,8\cdot x+32\right]=60\)
\(\Rightarrow2,8\cdot x+32=60\)
\(\Rightarrow2,8\cdot x=60-32\)
\(\Rightarrow2,8\cdot x=28\)
Đến đây dễ rồi :v