1: x=7+5=12

2: =>-29-x=-10

=>x+29=10

=>x=-19

3: =>x+7=-18

=>x=-25

4: =>x+19-11=0

=>x+8=0

=>x=-8

a, 71.2 – 6.(2x+5) =  10 5 : 10 3

71.2 – 6.(2x+5) =  10 2

6.(2x+5) = 71.2 – 100

6.(2x+5) = 42

x = 1

b,  5 x + 3 4 . 6 8 = 6 9 . 3 4

5 x + 3 4 . 6 8 = 6 8 . 6 . 3 4

5 x + 3 4 = 6 8 . 6 . 3 4 : 6 8 = 6 . 3 4

5x =  6 . 3 4 - 3 4 = 5 . 3 4

x =  3 4

c, 12:{390:[5. 10 2  – ( 5 3 + x . 7 2 )]} = 4

390:[5. 10 2  – ( 5 3 + x . 7 2 )] = 12:4 = 3

5. 10 2  – ( 5 3 + x . 7 2 ) = 390:3 = 130

5 3 + x . 7 2 = 5. 10 2  – 130 = 370

x . 7 2 = 370 –  5 3 = 245

x = 245: 7 2 = 5

d,  5 3 .(3x+2):13 =  10 3 : 13 5 : 13 4

5 3 .(3x+2):13 =  10 3 : 13

3x+2 =  10 3 : 13 : 5 3 .13 = 8

x = 2

49 x 37 = 37 x 49

(214 x 25) x 4 = 214 x (25 x 4)

103 x 18 + 103 x 12 = 103 x (18 + 12)

49

214

12

\(2436\cdot\left(5\cdot x+103\right)=12\)

\(5\cdot x+103=2436:12=203\)

\(5\cdot x=203-103=100\)

\(x=100:5=20\)

\(2436.\left(5x+103\right)=12\)

\(5x+103=12:2436\)

\(5x+103=12:2436\)

\(5x+103=\frac{1}{2003}\)

\(5x=\frac{1}{2003}-103\)

\(5x=\frac{-206308}{2003}\)

\(x=\frac{-206308}{2003}.\frac{1}{5}\)

\(x=\frac{-206308}{10015}\)

\(2436\times\left(5\times x+103\right)=12\)

\(\Rightarrow5\times x+103=12:2436\)

\(\Rightarrow5\times x+103=\frac{1}{203}\)

\(\Rightarrow5\times x=\frac{1}{203}-103\)

\(\Rightarrow5\times x=-\frac{20908}{203}\)

\(\Rightarrow x=-\frac{20908}{203}:5\)

\(\Rightarrow x=...\)

Bn tự tính nha !

Hok tốt #

Vì x chia 6 dư 3; chia 8 dư 5; chia 12 dư 9

=> x-3 chia hết cho 6;8;12

=> x-3 \(\in\) BC(6;8;12) = {0;24;48;72;96;120;...;240;264;288;312;...}

=> x \(\in\) {3;27;51;75;...;243;267;291;315;...}

Mà 264 <x\(\le\) 300 => x \(\in\) {267;291}

a, 315-x=327-264

<=> 315-x=63

<=> x=315-63

<=>x=252

b, 147-x=10 x 5

<=> 147-x=50

<=> x= 147-50

<=> x=97

\(\left(315-x\right)+264=327\)

\(\left(315-x\right)=63\)

\(x=315-63\)

\(x=252\)

\(\left(147-x\right):5=10\)

\(\left(147-x\right)=50\)

\(x=147-50\)

\(x=97\)

( 315 - \(x\)) + 264 = 327

315 - \(x\) = 327 - 264

315 - \(x\) = 63

         \(x\) = 315 - 63

        \(x\) = 252

(147 - \(x\)) : 5 = 10

147 - \(x\) =10 \(\times\) 5

147 - \(x\) = 50

          \(x\) = 147 - 50

           \(x\) = 97 

Ta có \(131x-941=16\)

\(\Rightarrow131x=957\)

\(\Rightarrow x=\frac{957}{131}\)

b.\(12.\left(x-1\right):3=103\)

\(\Rightarrow12.\left(x-1\right)=309\)

\(\Rightarrow x-1=\frac{103}{4}\)

\(\Rightarrow x=\frac{107}{4}\)

a) x = 957/131

b) x = 107/4

học tốt

131 . x -941 =  16

131.x = 16+941

131.x =957

x=957:131

x=957/131

12 (x-1) :3 =103

12 (x - 1 )=103 . 3

12 (x -1 ) = 309

x-1=309:12

x-1 = 25,75

x= 25,75+1

x=26,75

a) 

1 2 + − 3 5 + 1 10 ≤ x ≤ 8 3 + 14 6 ⇔ 0 ≤ x ≤ 5 x ∈ 0 ; 1 ; 2 ; 3 ; 4 ; 5

b) 

11 3 + − 19 6 + − 15 2 ≤ x ≤ 19 12 + − 5 4 + − 10 3 ⇔ − 7 ≤ x ≤ − 3 x ∈ − 7 ; − 6 ; − 5 ; − 4 ; − 3