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Bài 1 :
a, \(\frac{3}{4}:x=\frac{5}{12}\)
\(x=\frac{3}{4}:\frac{5}{12}\)
\(x=\frac{9}{5}\)
b, \(x-\frac{1}{2}=\frac{3}{4}:\frac{3}{2}\)
\(x-\frac{1}{2}=\frac{1}{2}\)
\(x=\frac{1}{2}+\frac{1}{2}\)
\(x=1\)
c, \(1\frac{1}{2}x-\frac{1}{2}=\frac{3}{4}\)
\(\frac{3}{2}x-\frac{1}{2}=\frac{3}{4}\)
\(\frac{3}{2}x=\frac{3}{4}+\frac{1}{2}\)
\(\frac{3}{2}x=\frac{5}{4}\)
\(x=\frac{5}{4}:\frac{3}{2}\)
\(x=\frac{5}{6}\)
Bài 2 :
\(A=\frac{-3}{5}+\left(\frac{-2}{5}-99\right)\)
\(A=\frac{-3}{5}+\frac{-2}{5}-99\)
\(A=\left(-1\right)-99\)
\(A=-100\)
\(B=\left(7\frac{2}{3}+2\frac{3}{5}\right)-6\frac{2}{3}\)
\(B=\left(\frac{23}{3}+\frac{13}{5}\right)-\frac{20}{3}\)
\(B=\frac{23}{3}+\frac{13}{5}-\frac{20}{3}\)
\(B=\left(\frac{23}{3}-\frac{20}{3}\right)+\frac{13}{5}\)
\(B=1+\frac{13}{5}\)
\(B=\frac{18}{5}\)
a) (-2) . ( x+7 ) + (-5) = 7
<=>(-2).(x+7)=7+5
<=>x+7=12:(-2)
<=>x+7=-6
<=>x=(-6)-7
<=>x=-13
Vậy x=-13
b)(x+4) : (-7) = 14
<=>x+4=14 x (-7)
<=>x+4=-98
<=>x=-98-4
<=>x=-102
Vậy x= -102
c) 72 : ( x+5) - 4 = -12
<=>72:(x+5)=(-12)+4
<=>x+5=72:(-8)
<=>x+5=-9
<=>x=-9-5
<=>x=-14
Vậy x= -14
d) (x+3) : (-6 ) + 12 = 8
<=>(x+3) :(-6)=8-12
<=>x+3=(-4)x(-6)
<=>x+3=24
<=>x=24-3
<=>x=21
Vậy x= 21
bạn đã kiểm tra kĩ chưa vậy?mình đọc đề câu B mà loạn não luôn á;-;
tự tính đi em,giá trị tuyệt đối thì có 2 TH âm và dương nha em.Chúc em học tốt ,maays câu như này thì động não là được nhá
a, -7 + |x-4| = -3
|x-4| = -3-(-7)=4
=> x-4 = 4 hoặc x-4=-4
TH1: x-4=4 => x=8
TH2: x-4=-4 => x=0
Vậy x=8 hoặc x=0
b, 13 - |x+5| = 13
|x+5| = 13 - 13 = 0
=> x+5 = 0
x = 0-5 = -5
Vậy x=-5
c, |x-10| - (-12) = 4
|x-10| = 4 + (-12) = -8 ( vô lý )
=> \(x\in\varnothing\)( Không có trường hợp nào của x thỏa mãn đề bài )
Vậy \(x\varnothing\in\)
Chúc bạn học tốt ^^!!!
a)\(-\frac{12}{7}\cdot\left(\frac{3}{4}-x\right)\cdot\frac{1}{4}=0\)
=>\(\frac{3}{4}-x=0\)
=>\(x=\frac{3}{4}\)
Vậy \(x=\frac{3}{4}\)
b) \(x:\frac{17}{8}=-\frac{2}{5}\cdot\left(-\frac{9}{17}\right)\)
=>\(x:\frac{17}{8}=\frac{18}{85}\)
=>\(x=\frac{18}{85}\cdot\frac{17}{8}=\frac{9}{20}\)
Vậy \(x=\frac{9}{20}\)
a) 3/8 . x = 9/8 - 1
3/8 . x = 1/8
x = 1/8 : 3/8
x = 1/3
b) 4/5 . x = 7/5 - 1/5
4/5 . x = 6/5
x = 6/5 : 4/5
x = 3/2
c) 12/7 : x + 2/3 = 7/5
12/7 : x = 7/5 - 2/3
12/7 : x = 11/15
x = 12/7 : 11/15
x = 180/77
d) 3.(x + 7) - 15 = 27
3.(x + 7) = 27 + 15
3.(x + 7) = 42
x + 7 = 42 : 3
x + 7 = 14
x = 14 - 7
x = 7
a) \(\dfrac{3}{8}x=\dfrac{9}{8}-1\)
\(\Rightarrow\dfrac{3}{8}x=\dfrac{1}{8}\)
\(\Rightarrow x=\dfrac{1}{8}:\dfrac{3}{8}=\dfrac{1}{3}\)
b) \(\dfrac{4}{5}x=\dfrac{7}{5}-\dfrac{1}{5}\)
\(\Rightarrow\dfrac{4}{5}x=\dfrac{6}{5}\)
\(\Rightarrow x=\dfrac{6}{5}:\dfrac{4}{5}=\dfrac{3}{2}\)
c) \(\dfrac{12}{7}:x+\dfrac{2}{3}=\dfrac{7}{5}\)
\(\Rightarrow\dfrac{12}{7}:x=\dfrac{7}{5}-\dfrac{2}{3}\)
\(\Rightarrow\dfrac{12}{7}:x=\dfrac{11}{15}\)
\(\Rightarrow x=\dfrac{12}{7}:\dfrac{11}{15}=\dfrac{180}{77}\)
d) \(3\left(x+7\right)-15=27\)
\(\Leftrightarrow3\left(x+7\right)=42\)
\(\Leftrightarrow x+7=14\Leftrightarrow x=7\)
`a, x/7 =-4/14`
`=> 14x=7.(-4)`
`=>14x=-28`
`=>x=-28:14`
`=>x=-2`
`b,x/2=-2/-x`
`=>x/2=2/x`
`=>x.x=2.2`
`=>x^2=4`
`=>x= +-2`
`c,(x-1)/5=5/(x-1)`
`=>(x-1)^2 = 5.5`
`=>(x-1)^2=25`
`=>(x-1)^2=5^2`
\(\Rightarrow\left[{}\begin{matrix}x-1=5\\x-1=-5\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=6\\x=-4\end{matrix}\right.\)
`d,x+3/2=-12/16`
`=>x=-12/16 -3/2`
`=>x= -12/16 - 24/16`
`=>x= -36/16`
`=>x=-9/4`
a) x + 12 = (-5) - x
=> chuyển vế : x + x = -12 - 5
=> 2x = -17
=> x = \(-\frac{17}{2}\)
b) 2 . (x - 1) + 3 . (x-2) = x - 4
=> 2x - 2 + 3x - 6 = x - 4
=> chuyển vế: 2x +3x - x = 2 + 6 - 4
=> 4x = 4 => x = 1
c) 4 . (2x +7) - 3 . (3x-2) = 24
=> 8x + 28 - 9x +6 = 24
=> - x = -28 - 6 + 24
=> x = 10
d) 3 . ( x-2) + 2x = 10 (Ý bạn c là x đúng không?)
=> 3x - 6 + 2x = 10
=> 5x = 6 + 10
=> 5x = 16 => x = \(\frac{16}{5}\)
Đúng thì k mik nha. Thanks!
\(a,x+12=\left(-5\right)-x\)
\(x+x=12-5\)
\(2x=7\Leftrightarrow x=\frac{7}{2}\)
\(b,2\left(x-1\right)+3\left(x-2\right)=x-4\)
\(2x-2+3x-6=x-4\)
\(2x+3x-x=-4+2+6\)
\(4x=4\Leftrightarrow x=1\)
\(c,4\left(2x+7\right)-3\left(3x-2\right)=24\)
\(4x+28-9x+6=24\)
\(4x-9x=24-28-6\)
\(-5x=-10\Leftrightarrow x=2\)
\(d,3\left(x-2\right)+2x=10\)
\(3x-6+2x=10\)
\(3x+2x=10+6\)
\(5x=16\Leftrightarrow x=\frac{16}{5}\)
a, 100 - 7 ( x - 5 ) = 31 + 33
100 - 7 ( x - 5 ) = 31 + 27
100 - 7 ( x - 5 ) = 58
7 ( x - 5 ) = 100 - 58
7 ( x - 5 ) = 42
x - 5 = 42 : 7
x - 5 = 6
=> x = 6 +5
=> x = 11
Vậy x = 11
b, 12 ( x - 1 ) : 3 = 43 + 23
12 ( x - 1 ) : 3 = 64 + 8
12 ( x - 1 ) : 3 = 72
12 ( x - 1 ) = 72 . 3
12 ( x - 1 ) = 216
x - 1 = 216 : 12
x - 1 = 18
=> x = 18 + 1
=> x = 19
Vậy x = 19
c, 24 + 5x = 75 : 73
24 + 5x = 72
24 + 5x = 49
5x = 49 - 24
5x = 25
=> x = 25 : 5
=> x = 5
Vậy x = 5
d, 5x - 206 = 24 . 4
5x - 206 = 16 . 4
5x - 206 = 64
5x = 64 + 206
5x = 270
=> x = 270 : 5
=> x = 54
Vậy x = 54
e, 125 = x3
53 = x3
=> x = 5
Vậy x = 5
g, 64 = x2
82 = x2
=> x = 8
Vậy x = 8
\(-\dfrac{3}{4}+x=-\dfrac{7}{12}\\ x=-\dfrac{7}{12}-\left(-\dfrac{3}{4}\right)\\ x=-\dfrac{7}{12}+\dfrac{3}{4}\\ x=\dfrac{-7+3.3}{12}\\ x=\dfrac{-7+9}{12}\\ x=\dfrac{2}{12}=\dfrac{1}{6}\)
\(\dfrac{-3}{4}+x=-\dfrac{7}{12}\)
\(x=\dfrac{-7}{12}-\dfrac{-3}{4}\)
\(x=\dfrac{-7}{12}+\dfrac{9}{12}\)
\(x=\dfrac{2}{12}=\dfrac{1}{6}\)