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\(\left|x+2\right|=0\)
\(\Rightarrow x+2=0\)
\(\Rightarrow x=0-2\)
\(\Rightarrow x=-2\)
\(\left|x-5\right|=\left|-7\right|\)
\(\Rightarrow\left|x-5\right|=7\)
\(\Rightarrow\hept{\begin{cases}x-5=-7\\x-5=7\end{cases}}\Leftrightarrow\hept{\begin{cases}x=-7+5\\x=7+5\end{cases}}\Leftrightarrow\hept{\begin{cases}x=-2\\x=12\end{cases}}\)
\(\Rightarrow x\in\left\{-2;12\right\}\)
x-7=-5
x=-5+7
x=2
vậy x=2
128-3.(x+4)=23
3.(x+4)=128-23
3.(x+4)=105
x+4=105:3
x+4=35
x=35-4
x=31
vậy x=31
|x+2|=0
x+2=0
x=0-2
x=-2
vậy x=-2
|x-5|=|-7|
x-5=7
x=7+5
x=12
vậy x=12
1)
a) 35.23 + 35.41 + 64.65 = 35(23+41) + 64.65 = 35 . 65 + 64.65 =65. 99 = 65(100 - 1 ) = 6500 - 65 = 6435
b) 29.87 - 29.23 + 64.71 = 29(87-23) + 64.71 = 29.64 + 64.71 = 64(71+29) = 64.100= 6400
c) 48.19 + 48.115 + 134.52 = 48(19+115) + 134.52 = 48 . 134+134.52=134(52+48)=134.100=13400
d) 27.121 - 87.27 + 73.34 = 27(121-87) +73 .34 = 27 .34 + 73.34 = 34(73+27)=34.100=3400
e) 125.98-125.46-52.25 = 125(98-46) -52.25 = 125 . 52 - 52.25 =52(125-25) =52.100=5200
f)136.23 + 136.17 - 40.36 = 136(23+17) - 40.36 = 136.40 -40.36 = (136-36)40 = 100.40=4000
g) 17.93 + 116.83 + 17.23 = 17(93+23) + 116.83 = 17.116 + 116.83 =116(83+17) = 116.100=11600
h)19.27 +47.81 + 19.20 = 19(27+20) + 47.81 = 19. 47 + 47.81 = 47(81+19)=47.100 = 4700
i) 87.23 + 13.93 + 70.87 = 87(23+70) + 13.93 = 87 .93 + 13.93 = 93(87+13)=93.100=9300
2)Tìm x
a) [(6x-39):37].4 = 12
(6x - 39) : 37 = 12 : 4 = 3
x =(3.37 + 39): 6 = 25
b) ( x : 3 - 4 ) .5=15
x : 3 -4 = 3
x = (3+4).3 = 21
c) 128 - 3(x+4) =23
3x + 12 = 128 -23 = 105
x = (105-12):3 = 31
d) (3x - 34).73=2.74
3x - 81 = 2.74:73=2.7=14
x =(81 + 14 ) : 3= \(31\frac{2}{3}\)
e) x - [42 + (-28) ] = -8
x - 14 = -8
x- 14 + 14 = -8 + 14
x = 6
d, \(\left(3x-2^4\right).7^3=2.7^4\)
\(\Rightarrow3x-2^4=2.7^4:7^3\)
\(\Rightarrow3x-16=2.7\\ \Rightarrow3x=14+16\\ \Rightarrow3x=30\Rightarrow x=10\)
Vậy.....
e, \(x-\left[42+\left(-28\right)\right]=-8\)
\(\Rightarrow x-14=-8\\ \Rightarrow x=6\)
Vậy.....
g, \(x-7=-5\)
\(\Rightarrow x=-5+7\Rightarrow x=2\)
Vậy.....
h, \(15-5\left(x+4\right)=-12-3\)
\(\Rightarrow15-5x-20=-15\)
\(\Rightarrow-5x=-15-15+20\)
\(\Rightarrow-5x=-10\Rightarrow x=2\)
Vậy.....
Chúc bạn học tốt!!!
d/ \(\left(3x-2^4\right)\cdot7^3=2\cdot7^4\)
\(\Rightarrow3x-16=\dfrac{2\cdot7^4}{7^3}=14\)
\(\Rightarrow3x=14+16=30\)
\(\Rightarrow x=\dfrac{30}{3}=10\)
e/ Đễ ==> tự lm thì tốt hơn nhé
g/ Đễ ==> tự lm thì tốt hơn nhé
h/ \(15-5\left(x+4\right)=-12-3\)
\(\Rightarrow15-5x-20=-15\)
\(\Rightarrow-5x=-15+20-15=-10\)
\(\Rightarrow x=\dfrac{-10}{-5}=2\)
i/ \(\left(7-x\right)-\left(25+7\right)=-25\)
\(\Rightarrow7-x-25-7=-25\)
\(\Rightarrow-x=-25-7+7+25\)
\(\Rightarrow-x=0\Rightarrow x=0\)
k/ \(\left|x+2\right|=0\Rightarrow x+2=0\Rightarrow x=-2\)
l/ \(\left|x-3\right|=7-\left(-2\right)\)
\(\Rightarrow\left|x-3\right|=9\)
\(\Rightarrow\left[{}\begin{matrix}x-3=9\\x-3=-9\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=12\\x=-6\end{matrix}\right.\)
m/ \(\left|x-5\right|=\left|-7\right|\Rightarrow\left|x-5\right|=7\)
\(\Rightarrow\left[{}\begin{matrix}x-5=7\\x-5=-7\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=12\\x=-2\end{matrix}\right.\)
a) x - 7 = -5
\(\Leftrightarrow x=-5+7=2\)
b) 128 - 3(x + 4) = 23
\(\Leftrightarrow128-3x-12=23\)
\(\Leftrightarrow-3x=23+12-128\)
\(\Leftrightarrow-3x=-93\)
\(\Leftrightarrow x=31\)
c) x - [42 + (-28)] = -8
\(\Leftrightarrow x-42+28=-8\)
\(\Leftrightarrow x=-8+42-28=6\)
d) (7 - x) - (25 + 7) = -25
\(\Leftrightarrow7-x-25-7=-25\)
\(\Leftrightarrow-x=-25+25+7-7\)
\(\Leftrightarrow x=0\)
a) x - 7 = - 5
x = - 5 + 7
x = 2
b) 128 - 3 . ( x + 4 ) = 23
3 . ( x + 4 ) = 128 - 23
3 . ( x + 4 ) = 105
x + 4 = 105 : 3
x + 4 = 35
x = 35 - 4
x = 31
c) [ ( 6x - 39 ) : 7 ] . 4 = 12
( 6x - 39 ) : 7 = 12 : 4
( 6x - 39 ) : 7 = 3
6x - 39 = 3 . 7
6x - 39 = 21
6x = 60
x = 10
d) ( x : 3 - 4 ) . 5 = 15
x : 3 - 4 = 3
x : 3 = 7
x = 21
a) x - 7= -5
x= -5 +7
x= 2
b) 128 -3 .(x+4)=23
3.(x+4)=128-23
3.(x+4)=105
x+4=105:3
x+4=35
x=35-4
x=31
c)[(6x-39):7].4=12
[(6x-39):7]=12:4
(6x-39):7=3
6x-39=7.3
6x-39=21
6x=21+39
6x=60
x=60:6
x=10
d) ( x :3 -4).5=15
x:3-4=15:5
x:3-4=3
x:3=4+3
x:3=7
x=7.3
x=21
e)(3x -2^4 ).7^3=2. 7^4
(3x-16).343=2.2401
(3x-16).343=4802
3x-16=4802:343
3x-16=14
3x=14+16
3x=30
x=30:3
x=10
g)x-[ 42+(-28)]=-8
x-14=-8
x=-8+14
x=6
i) 4-(7-x)=x -(13-4)
4-7+x=x-13+4
-3 + x= x-9
-3+x=-9+x
=> K có giá trị nào thỏa mãn -3+x=-9+x
=>x thuộc rỗng
1. Tính nhanh:
a, 35.23+35.41+64.65
= 35. (23+41) +64.65
= 35. 64 + 64.65
= 64. ( 35 + 65 )
= 64 . 100
= 6400
b, 29.87 - 29.23 + 64.71
= 29.(87-23) + 64.71
= 29.64 + 64.71
= 64.(29 + 71)
= 64.100
= 6400
c, 48.19 + 48.115 + 134.52
= 48.(19 + 115) + 134.52
= 48.134 + 134.52
= 134.(48 + 52)
= 134.100
= 13400
d, 27.121 - 87.27 + 73.34
= 27.(121 - 87) + 73.34
= 27.34 + 73.34
= 34.(27 + 73)
= 34.100
= 3400
e, 125.98 - 125.46 - 52.25
= 125.(98 - 46) - 52.25
= 125.52 - 52.25
= 52.(125 - 25)
= 52.100
= 5200
f, 136.23 + 136.17 - 40.36
= 136.(23 + 17) - 40.36
= 136.40 - 40.36
= 40.(136 - 36)
= 40.100
= 4000
g, 17.93 + 116.83 + 17.23
= 17.(93+23) + 116.83
= 17.116 + 116.83
= 116.(17 + 83)
= 116.100
= 11600
Lát nữa mình làm tiếp, giờ mình phải đi học rồi
[ ( 6x - 39 ) : 7 ] . 4 = 12
=> ( 6x - 39 ) : 7 = 12 : 4
=> ( 6x - 39 ) : 7 = 3
=> 6x - 39 = 3.7
=> 6x - 39 = 21
=> 6x = 21+39
=> 6x = 60
=> x = 10.
( x : 3 - 4 ) . 5 = 15
=> x : 3 - 4 = 15 : 5
=> x : 3 - 4 = 3
=> x : 3 = 7
=> x = 7.3
=> x = 21
x - [ 42 + (-28) ] = -8
=> x - 14 = -8
=> x = -8 + 14
=> x = 6.
[ (6x - 39): 7] . 4=12
(6x-39) : 7=12:4
(6x -39) :7=3
(6x-39) =3 . 7
6x-39 =21
6x =21 +39
6x=20
x=10
