Bài 1 a) 45 - x - 9 = 6
=> 36 -x = 6
=>x = 30
b) 11x - 99 = 77
=> 11x = 176
=> x = 16
c) 25 + 3x - 24 =106
=> 3x = 105
=> x = 35
d) 7x - 5 = 21
=> 7x = 26
=> x = 26/7
e) 156 - 2x = 82
=> 2x = 74
=> x = 37
Bài 2
136. 23 + 136.17 - 40 . 36
= 136 ( 23 + 17 ) - 40 .36
= 136 . 40 - 40 . 36
= 40 ( 136 - 36 )
= 40 . 100
= 4000
1a. 45 - (x + 9) = 6
x + 9 = 45 - 6
x = 39 - 9
x = 30
b. 11. (x - 9) = 77
x - 9 = 77 : 11
x = 7 + 9
x = 16
c. 25 +3. (x - 8) = 106
3(x - 8) = 106 - 25
x - 8 = 81 : 3
x = 27 + 8
x = 35
d. 7(x - 5) = 21
x - 5 = 21 : 7
x = 3 + 5
x = 8
e. 156 - 2x = 82
2x = 156 - 82
x = 74 : 2
x = 37
2. 136 . 23 + 136 . 17 - 40 . 136
= 136 . (23 + 17 - 40)
= 136 . 0
= 0
Bài 1: tìm x
a) 45-( x+ 9) = 6
x + 9 = 45 - 6
x + 9 = 39
x = 39 - 9
x = 30
b)11.(x-9)=77
x - 9 = 77 : 11
x - 9 = 7
x = 7 + 9
x = 16
c ) 25+3.(x-8) =106
3 . ( x - 8 ) = 106 - 25
3 . ( x - 8 ) = 81
x - 8 = 81 : 3
x - 8 = 27
x = 27 + 8
x = 35
d ) 7. x - 5 = 21
7 . x = 21 + 5
7 . x = 26
x = 26 : 7
x = 26/7
e ) 156 - 2 .x= 82
2 . x = 156 - 82
2 . x = 74
x = 74 : 2
x = 37
Bài 2: tính nhanh
136 . 23 +136 .17 -40 . 36
= 136 . ( 23 + 17 ) - 40 . 36
= 136 . 40 - 40 . 36
= 40 . ( 136 - 36 )
= 40 × 100
= 4 000
a) 45-(x+9)=6
x+9=45-6
x+9=39
x=39-9
x=30
vậy...
b) 11.(x-9)=77
x-9=77:11
x-9=7
x=7+9
x=16
vậy...
c)25+3.(x-8)=106
3.(x-8)=106-25
3.(x-8)=81
x-8=81:3
x-8=27
x=27+8
x=35
vậy....
