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a) 450 : ( 50 - 7x ) = 30
=> 50 - 7x = 15
=> 7x = 35
=> x =5
Vậy x=5
b) 14x - 2x = 120
=> x ( 14 - 2 ) = 120
=> x . 12 = 120
=> x =10
Vậy x = 10
c) x.13 - x.10 = 240
=> x ( 13 - 10 ) = 240
=> x. 3 = 240
=> x = 80
Vậy x = 80
d) 28x - 17x - x = 250
=> x( 28 - 17 - 1 ) = 250
=> x. 10 = 250
=> x = 25
Vậy x = 25
e) 34x - 14x = 200
=> x ( 34 - 14 ) = 200
=> x.20 = 200
=> x = 10
Vậy x = 10
f) 280 - x.9 - x =80
=> x.9 - x = 200
=> x ( 9 -1 ) = 200
=> x.8 = 200
=> x = 25
Vậy x = 25
a) 450 : (50-7.x) = 30
Ta có: 50-7.x = y
=> 450 : y = 30
y = 15
=> 50-7. x= 15
7x = 35
x= 5
vậy x = 5
(bạn ơi câu này mình trả lời đúng nhưng cách làm thì hơi khác 1 tí)
b) x.14 - x.2 = 120
x . (14-2) = 120
x . 12 = 120
x = 120 : 12
x = 10
Vậy x= 10
c) x.13 - x.10 = 240
x . (13-10) = 240
x . 3 = 240
x = 80
Vậy x = 80
d) 28.x - x.17-x = 250
28.x - x.17 - x.1 = 250
=> x. (28-17-1) = 250
x. 10 = 250
x = 25
Vậy x=25
e) x.34-x.14 = 200
x. ( 34-14) = 200
x. 20 = 200
x = 10
vậy x = 10
f) 280 - x.9 - x = 80
280 - x.9 - x.1 = 80
280 - x.( 9-1) = 80
280 - x.8 = 80
x.8 = 200
x = 25
vậy x = 25
\(6\cdot x-5=613\)
\(6\cdot x=613+5\)
\(6\cdot x=618\)
\(x=618\div6\)
\(x=103\)
Vậy \(x=103\)
\(12\cdot x+3\cdot x=30\)
\(x\cdot\left(12+3\right)=30\)
\(x\cdot15=30\)
\(x=30\div15\)
\(x=2\)
Vậy \(x=2\)
\(125-25\cdot\left(x-1\right)=100\)
\(25\cdot\left(x-1\right)=125-100\)
\(25\cdot\left(x-1\right)=25\)
\(x-1=25\div25\)
\(x-1=1\)
\(x=1+1\)
\(x=2\)
Vậy \(x=2\)
\(\left(x-2\right)\cdot\left(x-14\right)=0\)
\(\Rightarrow\) \(x-2=0\) hoặc \(x-14=0\)
TH1: \(x-2=0\) TH2: \(x-14=0\)
\(x=0+2\) \(x=0+14\)
\(x=2\) \(x=14\)
Vậy \(x=2\) hoặc \(x=14\)
\(128-3\cdot\left(x+4\right)=23\)
\(3\cdot\left(x+4\right)=128-23\)
\(3\cdot\left(x+4\right)=105\)
\(x+4=105\div3\)
\(x+4=35\)
\(x=35-4\)
\(x=31\)
Vậy \(x=31\)
12.x+3.x=30
x.(12+3)=30
x.15=30
x =30:15
x =2
125-25.(x-1)=100
25.(x-1)=125-100
25.(x-1)=25
x-1=25:25
x-1=1
x =1+1
x=2
(x-2).(x-14)=0
x=14
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 =39
Bài 2:
a) \(\left(x-34\right).15=30\)
\(\Rightarrow x-34=2\)
\(\Rightarrow x=36\)
Vậy \(x=36\)
b) \(18\left(x-16\right)=18\)
\(\Rightarrow x-16=1\)
\(\Rightarrow x=17\)
Vậy \(x=17\)
a) 86 + 357 + 14
= (86 + 14) + 357
= 100 + 357
= 457
b) 72 + 69 + 128
= (72 + 128) + 69
= 200 + 69
= 269
c) 25 . 5 . 4 . 27 . 2
= (25 . 4) . (2 . 5) . 27
= 100 . 10 . 27
= 1000 . 27
= 27000
d) 28 . 64 + 28 . 36
= 28 . (64 + 36)
= 28 . 100
= 2800
2. Tìm số tự nhiên x ,biết
a) ( x - 34 ) . 15 = 30
(x - 34) = 30 : 15
(x - 34) = 2
x = 2 + 34
x = 36.
b) 18 . ( x - 16 ) = 18
( x - 16 ) = 18 : 18
( x - 16 ) = 1
x = 1 + 16
x = 17.
a) (247 x 514 x 213 x 913 x 517 x 917 ) : (230 x 230 x 530 x 930)
(260 x 531 x 930) : (260 x 530 x 930) = 5
1. 11(x-9)=77
x-9=7
x=16
2. 4(x-3)=48
x-3=12
x=15
3.3(x-8)=81
(x-8)=27
x=35
\(x-120:30=40\)
\(x-120=40.30=1200\)
\(x=1200+120=1320\)
Vậy. \(x=1320\)
a) x - 120 : 30 = 40
x - 4 = 40
x = 40 + 4
x = 44
b) (x - 120) : 35 = 5
x - 120 = 5.35
x - 120 = 175
x = 175 + 120
x = 295
c) (x + 100).4 = 800
x + 100 = 800 : 4
x + 100 = 200
x = 200 - 100
x = 100
d) x.5 + 10.9 = 990
5x + 90 = 990
5x = 990 - 90
5x = 900
x = 900 : 5
x = 180
e) x.14 - x.2 = 120
14x - 2x = 120
12x = 120
x = 120 : 12
x = 10
f) x.13 - x.10 = 240
13x - 10x = 240
3x = 240
x = 240 : 3
x = 80
g) 28.x - 17.x - x = 250
10x = 250
x = 250 : 10
x = 25
a,x=-2,-2,0,1
b, x-18=16x3
x-18=48 suy ra x = 66
c, 3x(x+4)=128-23
3x(x+4)=105
x(x+4)=105:3=35
x.x=x.4
x^2=4
x=2
a,=>x=(-2)-1;0;1
b,x-18=16.3
x-18=48
x=48+18
x=66
c,3(x+4)=128-23
3(x+4)=105
x+4= 105:3
x+4=35
x=35-4
x=31
Bài 1:
1; ( - 35) : (-7) = 5
2; (- 42) : 21 = - 2
3; 45 : (-9) = -5
4; 18 : 9 = 2
5; (- 30) : (- 15) = 2
6; 0 : 18 = 0
7; 0 : (-13) = 0
8; 44 : (-4) = - 11
9; - 55 : 11 = - 5
10; 46 : 23 = 2
Bài 2: Tìm số tự nhiên x biết:
a) 12(x−1)∶3=43+23 c) (7x−11)3=23.52+200
b) 128−3(x+4)=23 d) 2x+2−2x=96
`x-120 : 30 =40`
`x-4=40`
`x=40+4`
`x=44`
___________________
`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`
___________________________
` 274 - ( 9 . x + 18 ) = 4`
`9x+18=274-4`
`9x+18=270`
`9x=270 - 18`
`9x=252`
`x=252:9`
`x=28`
____________________________
`x.34-x.14=200`
`34x-14x=200`
`20x=200`
`x=200:20`
`x=10`
a, x = 44
b, x = 31
c, x = 28
d, x = 1000