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2.
c) /x-2/=9+15=24
x=26
hoạc
x=-22
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a) 29x - 13 = 45
29x = 58
x = 58/29 = 2
b) (168 - 2x) : 7 = 24
168 - 2x = 168
2x = 0
x = 0
c) x chia hết cho 8 và 15 < x < 60
=> x thuộc B(8) = {0 ; 8 ; 16 ; 24 ; ...... ; 56 ; .......}
Vì 15 < x < 60
x = { 24 ; 32 ; ..... ; 56 }
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a.x+8=âm 17
x = - 17 - 8
x = -25
b. ( x - 7 ) + 13 = 25
( x - 7 ) = 25 - 13
( x - 7 ) = 12
x = 12 + 7
x = 19
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B1
a.35*18-5*7*28
=35*18-35*28
=35*(-10)
=-350
b.24*(16-5)-16*(24-5)
=(24*16)-24*5-(16*24)-16*5
=384-24*5-384-16*5
=(384-384)-24*5-16*5
=0-24*5-16*5
=5*(-24-16)
=5*(-8)
=-40
c.29*(19-23)-19*(29-13)
=(29*19)-(19*29)*23-13
=(551-551)*23-13
=0*10
=0
d.34+35+36+37-14-15-16-17
=(34-14)+(35-15)+(36-16)+(37-17)
=20+20+20+20
=80
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Lời giải:
$\frac{x}{7}=\frac{5}{3}$
$x=7.\frac{5}{3}=\frac{35}{3}$
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$\frac{x+1}{6}=\frac{x-1}{7}$
$\Rightarrow 7(x+1)=6(x-1)$
$7x+7=6x-6$
$7x-6x=-6-7$
$x=-13$
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$\frac{5-3x}{4+2x}=\frac{-1}{3}$
$3(5-3x)=-(4+2x)$
$15-9x=-4-2x$
$-9x+2x=-4-15$
$-7x=-19$
$x=\frac{-19}{-7}=\frac{19}{7}$
![](https://rs.olm.vn/images/avt/0.png?1311)
a: x*3/4=1/5
=>x=1/5:3/4=1/5*4/3=4/15
b: x*3/7=2/5
=>x=2/5:3/7=2/5*7/3=14/15
c: 1/3+2/9=2/12x
=>1/6x=3/9+2/9=5/9
=>x=5/9*6=30/9=10/3
d: 4/15*x-2/3=1/5
=>4/15*x=2/3+1/5=10/15+3/15=13/15
=>4x=13
=>x=13/4
e: x:1/7=2/3
=>x=2/3*1/7=2/21
f: 1/9:x=7/3
=>x=1/9:7/3=1/9*3/7=3/63=1/21
j: 1/4+5/12=8/3:x
=>8/3:x=3/12+5/12=8/12=2/3
=>x=4
h: =>7/4:x=1/5+1/2=7/10
=>x=7/4:7/10=10/4=5/2
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=>29/7x-1=22/7
=>29/7x=29/7
hay x=1
\(\left(\dfrac{29x}{7}-1\right)-3=\dfrac{1}{7}\)
\(\dfrac{29x}{7}-1=\dfrac{1}{7}+3\)
\(\dfrac{29x}{7}-1=\dfrac{22}{7}\)
\(\dfrac{29x}{7}=\dfrac{22}{7}+1\)
\(\dfrac{29x}{7}=\dfrac{29}{7}\)
\(29.x:7=\dfrac{29}{7}\)
\(29.x=\dfrac{29}{7}\times7\)
\(29.x=29\)
\(x=29:29=1\)