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c ( 3x2 -6 ) - 43 = 53
( 3x2 -6 ) - 43 = 125
3x2 -6=125+43
3x2 -6=168
3x2=168+6
3x2=174
x2=174:3
x2=58(đề sai)
d) 3x + 2x ( 23 . 5 - 32 . 4 ) + 52 = 44
3x + 2x ( 8 . 5 - 9 . 4 ) + 25 = 256
3x + 2x.4 + 25 = 256
3x + 2x.4=256-25
3x + 2x.4=231
(3+2).x.4=231
5x.4=231
5x=231:4
5x=57,75
x=57,75:5
x=11,55
e) 720 : [ 41 - ( 2x - 5 ) ] = 23 . 5
720 : [ 41 - ( 2x - 5 ) ] =40
41 - ( 2x - 5 )=720:40
41 - ( 2x - 5 )=18
2x - 5=41-18
2x - 5=23
2x=23+5
2x=28
x=28:2
x=14
1440:[41-(2x-5)]=24.3
1440 : [41 - (2x - 5 ) ] = 48
41 - (2x - 5 ) = 1440 : 48
41 - ( 2x - 5 ) = 30
2x - 5 = 41 - 30
2x - 5 = 11
2x = 11 + 5
2x = 16
x= 16 : 2
x = 8
Bài 1 :
a) 1440 : [ 41 - (2x - 5)] = 24.3
=> 1440 : [41 - (2x - 5)] = 16.3
=> 1440 : [41 - (2x - 5)] = 48
=> 41 - (2x - 5) = 1440 : 48 = 30
=> 2x - 5 = 11
=> 2x = 16
=> x = 8
b) 5 . [225 - (x - 10)] - 125 = 0
=> 5 . [225 - (x - 10)] = 125
=> 225 - (x - 10) = 125 : 5
=> 225 - (x - 10) = 25
=> x - 10 = 200
=> x = 210
Bài 2 :
a) [ 545 - (45 + 4.25)] : 50 - 200 : 250 + 215 : 213
= [ 545 - (45 + 100)] : 50 - 4/5 + 22
= [545 - 145] : 50 - 4/5 + 4
= 400 : 50 - 4/5 + 4 = 8 - 4/5 + 4 =56/5
Mấy câu còn lại tương tự
Bài 1.
a, 1440:[41-(2x-5)]=24.3
1440:[41-(2x-5)]= 16.3
1440:[41-(2x-5)]=48
[41-(2x-5)] =1440:48
[41-(2x-5)] = 30
2x-5 = 41-30
2x-5 =11
2x = 11+5
2x = 16
x = 16:2
x =8
b, 5.[225-(x-10)]-125=0
5.[225-(x-10)] =125
[225-(x-10)] =125:5
[225-(x-10)] = 25
(x-10) = 225-25
(x-10) = 200
x =200+10
x = 210
Bài 2.
a, [545-(45+4.25)]:50-200:250+215:213
= [545-(45+100)]:50-200:250+22
= [545-145]:50- 200:250+4
= 400:50-200:250+4
= 8-0,8+4
= 7,2 + 4
= 11,4
b, [504-(25.8+70)]:9-15+190
= [504-(200+70)]:9-15+1
= [504-270]:9-16
= 234:9-16
= 26-16
= 10
c, 5.{26-[3.(5+2.5)+15]:15}
= 5.{26-[3.(5+10)+15]:15}
= 5.{26-[3.15+15]:15}
= 5.{26-[45+15]:15}
= 5.{26-60:15}
= 5.{26-4}
=5.22
= 110
d,[1104-(25.8+40)]:9+316:312
= [1104-(200+40)]:9+34
=[1104-240]:9+34
=864:9+81
=96+81
=177
hok tốt
a) đặt [41-(2x-5)] là a <=> 1440 : a = 48
=> a = 30 <=> [41-(2x-5)] = 30 => 41-(2x-5) =30
<=> -(2x-5) = -11 <=> 2x-5 = 11 <=> 2x = 16 <=> x=2
b) tương tự câu a
gợi ý đáp án : x = 210
a) 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
\(a.128-3\left(x+4\right)=23.\)
\(3\left(x+4\right)=128-23\)
\(3\left(x+4\right)=105\)
\(x+4=105:3=35\)
\(x=35-4=31\)
\(b.\left[\left(4x+28\right)\cdot3+55\right]:5=35\)
\(\left(4x+28\right)\cdot3+55=35\cdot5=175\)
\(\left(4x+28\right)\cdot3=175-55=120\)
\(4x+28=120:3=40\)
\(4x=40-28=12\)
\(x=12:4=3\)
\(1440:\left[41-\left(2x-5\right)\right]=2^4.3\)
\(\Rightarrow1440:\left[41-\left(2x-5\right)\right]=48\)
\(\Rightarrow41-\left(2x-5\right)=30\)
\(\Rightarrow2x-5=11\)
\(\Rightarrow2x=16\)
\(\Rightarrow x=8\)
Vậy \(x=8\)
\(1440:\left[41-\left(2x-5\right)\right]=2^4\cdot3\)
\(1440:\left[41-\left(2x-5\right)\right]=48\)
\(41-\left(2x-5\right)=\frac{1440}{48}=30\)
\(2x-5=41-30=11\)
\(2x=16\)
\(x=8\)