Bài 1:
a) 70 -5(x-3)=45 b)10+2.x=4.4.4.4.4 : 4.4.4
c)(x.3-21):4+108=114 d)231-(x-6)=1339:13
Bài 2:
a) S= 1+2+3+4+5+....+99+100+101+102
b) S= 101+103+105+....+197+199+201
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a,70 – 5.(x – 3) = 45
5.(x -3) = 70 - 45
5.(x – 3) = 25
x – 3 = 25 : 5
x – 3 = 5
x = 5 + 3
x = 8
Vậy x = 8
b,\(2x-138=8x9=72\)
\(2x=138+72=210\)
\(x=210:2=105\)
c,\(10+2x=4^2\)\(=16\)
\(2x=16-10=6\)
\(x=6:2=3\)
d, 231 – (x- 6) = 1339 : 13
231 – (x – 6) = 103
x – 6 = 231 – 103
x – 6 = 128
x = 128 + 6
x = 134
Vậy x = 134
2x - 138 = 23 . 32
2x - 138 = 72
2x = 72 + 138
2x = 210
x = 105
10 + 2x = 45 : 43
10 + 2x = 16
2x = 16 - 10
2x = 6
x= 3
a)13-2(x+1)=7
2.(x+1)=13-7
2.(x+1)=6
x+1=6/2
x+1=3
x=3-1
x=2
a, 13 - 2 ( x + 1 ) = 7
2 .( x + 1 ) = 13 - 7
2 .( x + 1 ) = 6
x + 1 = 6 : 2
x + 1 = 3
x = 3 - 1
x = 4
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a,231 - ( x - 6 ) = 1339 : 13
=> 231 - ( x - 6 ) = 103
=> x = 6 + 231 - 103
=> x = 1 34
b,
( 3x - 21 ) : 4 + 108 = 144
=> ( 3x - 21 ) : 4 = 144 - 108
=> ( 3x - 21 ) :4 = 36
=> 3x - 21 = 36.4
=> 3x - 21 = 144
=> 3x = 144 + 21
=> 3x = 165
=> x = 165 : 3
=> x = 55
[ .... ]
a) 2 * x - 138 = 8 * 9
2 * x - 138 = 72
2 * x = 210
x = 105
b) 231 - ( x - 6 ) = 1339 : 13
231 - x + 6 = 103
237 - x = 103
x = 134
c) 70 - 5 * ( x-3) = 45
5 * (x-3) = 25
x - 3 = 5
x = 8
cac phan con lai bn lm tuong tu nha
* 2*X-138=8*9
<=> 2*X-138=72
<=> 2*X=72+138
<=> 2*X=210
<=> X=210/2=105
*231-(X-6)=1339:13
<=> 231-(X-6)=103
<=> X-6=231-103
<=>X-6=128
<=>X=128+6=134
*70-5*(X-3)=45
<=>5*(X-3)=70-45
<=>5*(X-3)=25
<=>X-3=25/5
<=>X-3=5
<=>X=8
*10+2*X=16
<=>2*X=16-10
<=>2*X=6
<=>X=6/2=3
a) 70 - 5 (x - 3) = 45
5 (x - 3) =70-45
5 (x - 3) =25
(x - 3)=25:5
(x - 3)=5
x=5+3
x=8
b) 10 + 2.x = 4^5 : 4^3
10 + 2.x=4^2
10 + 2.x=16
2.x=16-10
2.x=6
x=6:2
x=3
c) 2x - 138 = 2^3 . 3^2
2x - 138 = 8.9
2x - 138 = 72
2x=72+138
2x=210
x=210:2
x=105
d) 231 - (x - 6) = 133 : 13
(đề sai)
Giải:
a) \(70-5\left(x-3\right)=45\)
\(5\left(x-3\right)=70-45\)
\(5\left(x-3\right)=25\)
\(x-3=25:5\)
\(x-3=5\)
\(x=5+3\)
\(x=8\)
70 - 5 ( x - 3 ) = 45
5 ( x - 3 ) = 70 - 45
5 ( x - 3 ) = 25
x - 3 = 25 : 5
x - 3 = 5
=> x = 8
10 + 2 . x = 45 : 43
10 + 2 . x = 42
10 + 2 . x = 16
2 . x = 16 + 10
2 . x = 26
=> x = 13
231 - ( x - 6 ) = 1339 : 13
231 - ( x - 6 ) = 103
x - 6 = 231 - 103
x - 6 = 128
=> x = 134
2 . x - 138 = 23 . 32
2 . x - 138 = 72
2 . x = 72 + 138
2 . x = 210
=> x = 105
\(70-5\left(x-3\right)=45\)
\(\Leftrightarrow70-5x+15=45\)
\(\Leftrightarrow85-5x=45\)
\(\Leftrightarrow5x=40\)
<=> \(x=8\)
Bài 1:
a) 70 - 5.(x-3) = 45
5.(x-3) = 25
x -3 = 5
x = 8
b) 10 + 2x = 4.4.4.4.4 : 4.4.4
10 + 2x = 16
2x = 6
x = 3
c) ( x.3 -21) : 4 + 108 = 114
(x.3 -21) : 4 = 6
x.3 -21 = 24
x.3 = 45
x = 15
d) 231 - ( x-6) = 1339 : 13
231 -x + 6 = 103
237 - x = 103
x = 134
Bài 2:
a) S = 1 + 2 + ...+ 101 + 102
S = ( 1 +102).102 : 2
S = 56 253
b) S = 101 + 103 + ...+ 199 + 201
S = ( 101 + 201) . 51 :2
S = 7 550