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Ta có \(\frac{9}{25}x+\frac{3}{5}.\frac{9}{25}x+\frac{3}{5}.18+\frac{9}{25}x+18=x\)
=> \(\frac{9}{25}x\left(1+\frac{3}{5}+1\right)+18\left(\frac{3}{5}+1\right)=x\)
=> \(\frac{117}{125}x+28,8=x\)
=> \(x-\frac{117}{125}x=28,8\)
=> \(\frac{8}{125}x=28,8\)
=> x = 450
Vậy x = 450
\(\frac{9}{25}x+\frac{3}{5}.\frac{9}{25}x+\frac{3}{5}.18+\frac{9}{25}x+18=x\)
\(x\left(\frac{9}{25}+\frac{9}{25}+\frac{9}{25}\right).\frac{3}{5}+\frac{3}{5}.18+18=x\)
\(x.\frac{3}{5}\left(\frac{27}{25}+18\right)+18=x\)
\(x.\frac{3}{5}\left(\frac{27}{25}+\frac{450}{25}\right)+18=x\)
\(x.\frac{3}{5}.\frac{477}{25}+18=x\)
\(x.\frac{1431}{125}+\frac{2250}{125}=x\)
\(x.\frac{3681}{125}=x\)
vậy chac tui làm sai rồi
b)
`15-3(3x+18)=36`
`=> 3(3x+18)=15-36`
`=> 3(3x+18)=-21`
`=> 3x+18=-21:3`
`=> 3x+18=-7`
`=> 3x=-7-18`
`=> 3x=-25`
`=> x=-25:3`
`=> x=-25/3`
c)
`-12+(3-x)=25`
`=>-12+3-x=25`
`=>-x=25+12-3`
`=>-x=34`
`=>x=-34`
d)
`100-90xx(x:2-1)=-10`
`=>90xx(x:2-1)=100-(-10)`
`=>90xx(x:2-1)=110`
`=>x:2-1=110:90`
`=>x:2-1=11/9`
`=>x:2=11/9 +1`
`=> x:2=20/9`
`=> x=20/9 xx2`
`=> x=40/9`
phần đầu sai đề
(-18+25)-(125-18+25)
=-18 + 25 -125 + 18 - 25
= -18 +25 +(-125) +18 + (-25)
= [(-18)+18] + [25 +(-25)] + (-125)
= 0 + 0 + (-125)
= -125
Bài 1:
\(10-|x-3|=16\)
\(\Rightarrow|x-3|=-6\)
Mà Ix-3I >= 0 với mọi x
Mà -6<0 => PT vô nghiệm
b) 25.(37+5) -63.(-25)+5.(-125)
= 25.42+63.25+5.25.(-5)
= 25.[42+25+5.(-5)]
= 25.[42+25-25]
= 25.42
=1050
c) 31 . (-18)+ 31.(-81)-31
= 31.(-18)+31.(-81)+31.(-1)
= 31.[-18+(-81)+(-1)]
= 31.(-100)
= -3100
Lời giải:
a. $(x+5)-20=123$
$x+5=123+20=143$
$x=143-5=138$
b.
$-18+(3-x)=25$
$3-x=25+18=43$
$x=3-43=-404
c. $4(x-2)+11=-13$
$4(x-2)=-13-11$
$4(x-2)=-24$
$x-2=-24:4=-6$
$x=-6+2=-4$
d.
$(x+10):(-20)=6$
$x+10=6(-20)=-120$
$x=-120-10=-130$
a)(x+5)-20=123
(x+5)=123+20
x+5=143
x=143-5
x=138
b)-18 + (3-x)=25
(3-x)=25-(-18)
3-X=43
x=3-43
x=-40
c)4.(x-2):(-20)=6
4.(x-2)=6.(-20)
4.(x-2)=-120
x-2=(-120):4
x-2=-30
x=(-30)+2
x=-28
d)
( x + 10 ) : ( - 20 ) = 6
x+10=6.(-20)
x+10=-120
x=(-120)-10
x=-130
b. -6x=18
=> x = 18 : (-6)
=> x = -3
c. 35-3.|x|=5.(23-4)
=> 35-3.|x|=5.(8-4)
=> 35-3.|x|=5.4
=> 35-3.|x|=20
=> 3.|x|=35-20
=> 3.|x|=15
=> |x|=5
=> x \(\in\){-5; 5}
d. => 10+2.|x|=2.(9-1)
=> 10+2.|x|=2.8
=> 10+2.|x|=16
=> 2.|x|=16-10
=> 2.|x|=6
=> |x|=3
=> x \(\in\){-3; 3}
\(b,-18+\left(3-x\right)=25\)
\(3-x=25-\left(-18\right)\)
\(3-x=43\)
\(x=3-43\)
\(x=-40\)
b) -18 + ( 3 - x) = 25
( 3 - x) = 25 - ( -18)
( 3 - x) = 43
x = 3 - 43
x = - 40
Chúc em học tốt!