a) 12 + ( 5 + x ) = 20 

⇔ 5 + x = 8

⇔ x = 3

Vậy x = 3

b) 120 + ( 50 + x ) = 180

⇔ 50 + x = 60

⇔ x = 10

Vậy x = 10

c) 175 + (  30 - x ) = 200

⇔ 30 - x = 25

⇔ x = 5

Vậy x = 5

d) 130 - ( 100 + x ) = 25

⇔ 100 + x = 105

⇔ x = 5

Vậy x = 5

e) 145 - ( 125 + x ) = 12

⇔ 125 + x = 133

⇔ x = 8

Vậy x = 8

j) 5 ( x + 12 ) + 22 = 92

⇔ 5x + 60 + 22 = 92

⇔ 5x + 82 = 92

⇔ 5x = 10

⇔ x = 2

Vậy x = 2

g) 3 ( x + 23 ) + 6 = 96

⇔ 3x + 69 + 6 = 96

⇔ 3x + 75 = 96

⇔ 3x = 21

⇔ x = 7

Vậy x = 7

Tìm x : 

a) 12 + ( 5 + x ) = 20

5 + x =20 - 12

5 +  x = 8

x = 3 

b) 120 + ( 50 + x ) = 180

50 + x = 180-120

50 + x = 60

x = 60 - 50

x = 10

c) 175 + ( 30 - x ) = 200

30 -x = 200 - 175

30 - x = 25

x = 30-25

x=5

d) 130- ( 100 +x ) =25

100 + x =130 - 25

100+x= 105

x=105-100

x=5

e) 145 - (125+x) = 12

125+x = 145-12

125+x=133

x= 133-125

x=8

j) 5 (x+12) +22 = 92 

5 ( x+12) = 92 -22

5 (x+12)=70

x+12=70 : 5

x + 12 = 14

x = 14-12

x=2

g) 2 (x+23) + 6 =96

2 (x+23) = 96 - 6

2 (x+23)= 90

x+23=90:2

x+23=45

x= 45-23

x=22

CHÚC BẠN HỌC TỐT

a) 12 + ( 5 + x ) = 20

=> 5 + x = 20 - 12

=> 5 + x = 8

=> x = 8 - 5

tìm x :

a) 12 + ( 5 + x ) = 20 

b) 120 + ( 50 + x ) = 180

c) 175 + (  30 - x ) = 200

d) 130 - ( 100 + x ) = 25

e) 145 - ( 125 + x ) = 12

j) 5 ( x + 12 ) + 22 = 92

g) 3 ( x + 23 ) + 6 = 96

giúp mk nha mn mk cần gấp

=> x = 3

b) 120 + ( 50 + x ) = 180

=> 50 + x = 180 - 120

=> 50 + x = 60

=> x = 60 - 50

=> x = 10

c) 175 + ( 30 - x ) = 200

=> 30 - x = 200 - 175

=> 30 - x = 25

=> x = 30 - 25

=> x = 5

d) 130 - ( 100 + x ) = 25

=> 100 + x  = 130 - 25

=> 100 + x = 105

=> x = 105 - 100 

=> x = 5

Bài 1 :

a) $(x-25)-130=0$

$=>x-25=0+130=130$

$=>x=155$

b) $125+(145-x)=175$

$=>145-x=175-125=50$

$=>x=95$

c) $315-(6x+80)=155$

$=>6x+80=315-155=160$

$=>6x=160-80=80$

$=>x=\dfrac{80}{6}=\dfrac{40}{3}$

d) $435+(6x-8)=457$

$=>6x-8=457-435=22$

$=>6x=22+8=30$

$=>x=5$

Bài 2 :

a) $5^2+12^2=25+144=169=13^2$

$=>5^2+12^2=13^2$ là số chính phương.

b) $2^3+3^2+32=8+9+32=49=7^2$

$=>2^3+3^2+32=7^2$ là số chính phương.

c) $3^2+3^3+3^4=108$ không là số chính phương.

d) $1^3+2^3=1+8=9=3^2$

$=>1^3+2^3=3^2$ là số chính phương.

e) $1^3+2^3+3^3=1+8+27=36=6^2$

$=>1^3+2^3+3^3=6^2$ là số chính phương.

f) $1^3+2^3+3^3+4^3=1+8+27+64=100=10^2$

$=>1^3+2^3+3^3+4^3=10^2$ là số chính phương.

1) Tìm x

\(a) (x-25)-130=0\)

\(x-25=0+130=130\)

\(x=130+25\)

\(x=155\)

\(b) 125+(145-x)=175\)

\(145-x=175-125\)

\(145-x=50\)

\(x=145-50=95\)

\(c) 315-(6x+80)=155\)

\(6x+80=315-155\)

\(6x+80=160\)

\(6x=160-80=80\)

\(x=80:6=\dfrac{40}{3}\)

\(d) 435+(6x-8)=457\)

\(6x-8=457-435=22\)

\(6x=22+8=30\)

\(x=30:6=5\)

a) \(\left[\left(x+32\right)-17\right].2=42\)

\(\left[\left(x+32\right)-17\right]=42:2\)

\(\left[\left(x+32\right)-17\right]=21\)

\(\left(x+32\right)=21+17\)

\(\left(x+32\right)=38\)

\(x=38-32\)

\(x=6\)

b) \(125+\left(145-x\right)=175\)

\(\left(145-x\right)=175-125\)

\(\left(145-x\right)=50\)

\(x=145-50\)

\(x=95\)

\(a,\Rightarrow6x+70=130\Rightarrow6x=60\Rightarrow x=10\\ b,\Rightarrow240=\left(x+70\right):14-40\\ \Rightarrow\left(x+70\right):14=280\\ \Rightarrow x+70=3920\Rightarrow x=3850\\ c,\Rightarrow x-15=75\Rightarrow x=90\\ d,\Rightarrow\left(x+175\right):5=680-30=650\\ \Rightarrow x+175=3250\Rightarrow x=3075\\ e,\Rightarrow x-4867=1004523\Rightarrow x=1009390\\ f,\Rightarrow x+32-17=24\Rightarrow x=9\\ g,\Rightarrow3\left(x+1\right)=54\Rightarrow x+1=18\Rightarrow x=17\\ h,\Rightarrow19\left(35:x+3\right)=152\\ \Rightarrow35:x+3=8\Rightarrow35:x=11\Rightarrow x=\dfrac{35}{11}\)

\(PT\Leftrightarrow\left(\dfrac{x-70}{130}-1\right)+\left(\dfrac{x-25}{175}-1\right)+\left(\dfrac{x-50}{150}-1\right)+\left(\dfrac{x-275}{25}+3\right)=0\)

\(\Leftrightarrow\left(x-200\right)\left(\dfrac{1}{130}+\dfrac{1}{175}+\dfrac{1}{150}+\dfrac{1}{25}\right)=0\Leftrightarrow x=200\).

Vậy...

a: 17-2x=9

=>2x=17-9=8

=>x=8/2=4

b: \(145-135\left(x-2\right)^2=10\)

=>\(135\cdot\left(x-2\right)^2=135\)

=>\(\left(x-2\right)^2=1\)

=>\(\left[{}\begin{matrix}x-2=1\\x-2=-1\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=3\\x=1\end{matrix}\right.\)

c: \(x\inƯ\left(36\right)\)

=>\(x\in\left\{1;-1;2;-2;3;-3;4;-4;6;-6;9;-9;12;-12;18;-18;36;-36\right\}\)

mà x>12

nên \(x\in\left\{18;36\right\}\)

d: \(x-1\in B\left(9\right)\)

=>\(x-1\in\left\{0;9;18;27;36;45;54;...\right\}\)

=>\(x\in\left\{1;10;19;28;37;46;55;...\right\}\)

mà 25<x<50

nên \(x\in\left\{28;37;46\right\}\)

a) \(70-\left(x-3\right)=45\)

\(x-3=70-45\)

\(x-3=25\)

\(x=25+3\)

\(x=28\)

b) \(12+\left(5+x\right)=20\)

\(5+x=20-12\)

\(5+x=8\)

\(x=8-5\)

\(x=3\)

c) \(130-\left(100+x\right)=25\)

\(100+x=130-25\)

\(100+x=105\)

\(x=105-100\)

\(x=5\)

d) \(175+\left(30-x\right)=200\)

\(30-x=200-175\)

\(30-x=25\)

\(x=30-25\)

\(x=5\)

e) \(\left(x+12\right)+22=92\)

\(x+12=92-22\)

\(x+12=70\)

\(x=70-12\)

\(x=58\)

f) \(95-\left(x+2\right)=45\)

\(x+2=95-45\)

\(x+2=50\)

\(x=50-2\)

\(x=48\)

a)

70 - (x - 3) = 45

x - 3 = 70 - 45 = 25

x = 25 + 3 = 28

Vậy x = 28

b)

12 + (5 + x) = 20

5 + x = 20 - 12 = 8

x = 8 - 5 = 3

Vậy x = 3

c)

130 - (100 + x) = 25

100 + x = 130 - 25 = 115

x = 115 - 100 = 15

Vậy x = 15

d)

175 + (30 - x) = 200

30 - x = 200 - 175 = 25

x = 30 - 25 = 5

Vậy x = 5

e)

(x + 12) + 22 = 92

x + 12 = 92 - 22 = 70

x = 70 - 12 = 58

Vậy x = 58

f)

95 - (x + 2) = 45

x + 2 = 95 - 45 = 50

x = 50 - 2 = 48

Vậy x = 48

câu c sai r kìa bạn

a,315+(125-x)=435

125-x=435-315

125-x=120

x=125-120

x=5

b,x:(111-99)=175

x:12=175

x=175.12

x=2100

a;315+(125-x)=435

           125-x=435-315

            125-x=120

                  x=125-120

                  x=5

b;x/(111-99)=175

x/12=175

x    =175*12