\(7x-x=5^{21}:5^{19}+3.2^2-7^0\)

\(6x=5^2+3.2-1\)

\(6x=25+12-1\)

\(6x=36\)

\(x=6\)

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Ta có :
7x - x = 5²¹ : 5¹⁹ . 3 . 2² - 70

=> 6x = 5²¹: 5¹⁹ + 3 . 2² - 70

=> 6x = 5² + 3. 4 - 1

=> 6x = 25 + 3 . 2 - 1

=> 6x = 25 + 6 - 1

=> 6x = 30

=> x = 30 : 6

=> x = 5

7x−x=521:519+3.22−70

6x=52+3.2−16x=52+3.2−1

6x=25+12−16x=25+12−1

6x=366x=36

x=6

a) \(5x+x=39-3^{11}:3^9\)    

\(\Leftrightarrow6x=39-3^2\)                    

\(\Leftrightarrow6x=30\)

\(\Leftrightarrow x=5\)

b) \(2^x:2^5=16\)

\(\Leftrightarrow2^x:2^5=2^4\)

\(\Leftrightarrow2^x=2^4.2^5\)

\(\Leftrightarrow2^x=2^9\)

\(\Leftrightarrow x=9\)

c) \(7x-x=5^{21}:5^{19}+3.2^2-7^0\)

\(\Leftrightarrow6x=5^2+3.4-1\)

\(\Leftrightarrow6x=36\)

\(\Leftrightarrow x=6\)

d) \(7x-2x=6^{17}:6^{15}+44:11\)

\(\Leftrightarrow5x=6^2+4\)

\(\Leftrightarrow5x=40\)

\(\Leftrightarrow x=8\)

a)⇔6x=39-3²                                             

   ⇔6x=30                                             

   ⇔ x=5                                                

b)2^x:2⁵=16

⇔2^x=2⁴.2⁵ 

⇔ 2^x=2⁹                                                   

⇔ x=9

c)⇔6x=5²+3.2²-1

  ⇔ 6x= 36

  ⇔ x=6

d)⇔5x=6²+4

   ⇔ 5x=40

   ⇔ x=8

a: \(\Leftrightarrow6x=30\)

hay x=5

b: \(\Leftrightarrow6x=25+12-1=36\)

hay x=6

A x=5

B x = 6 (36)

a: \(\Leftrightarrow8x=108+12=120\)

hay x=15

b: \(\Leftrightarrow6x=60\)

hay x=10

a) 5x + 3x = 120
    x . (5+3)= 120
    x . 8       = 120
    x            = 120 : 8
    x            = 15

c) 7x - 2x = 40
    x .(7-2)= 40
    x . 5     = 40

    x          = 40 : 5
    x          = 8

a: x-4/5=3/7

=>x=3/7+4/5=43/35

b: x+3/7=4/5

=>x=4/5-3/7=13/35

c: 19/20-x=8/5-3/4

=>19/20-x=32/20-15/20=17/20

=>x=2/20=1/10

d: =>4/5*x=2/21

=>x=2/21:4/5=5/42

e: =>x:7/9=6/8

=>x=6/8*7/9=3/4*7/9=21/36=7/12

f: =>x/6=2/3-1/3=1/3

=>x=2

a: x-4/5=3/7

=>x=3/7+4/5=43/35

b: x+3/7=4/5

=>x=4/5-3/7=13/35

c: 19/20-x=8/5-3/4

=>19/20-x=32/20-15/20=17/20

=>x=2/20=1/10

d: =>4/5*x=11/21

=>x=55/84

e: =>x=6/8*7/9=42/72=7/12

f: =>x/6=2/3-1/3=1/3

=>x=2

x - 4/5 = 3/7

x = 3/7 + 4/5

x = 43/35

x + 3/7 = 4/5

x = 4/5 - 3/7

x = 13/35

19/20 - x = 8/5 - 3/4

19/20 - x =  17/20

x = 19/20 - 17/20

x = 2/20 = 1/10

4/5 x X = 6/9 - 4/7

4/5 x X = 2/21

x = 2/21 : 4/5

x =5/42

x : 7/9 = 6/8

x = 6/8 x 7/9

x = 7/12

2/3 - x/6 = 6/18

x/6 = 2/3 - 6/18

x/6 = 1/3

x/6 = 2/6

=> x =2

1. x = 43/35

2. x = 13/35

3. x = 1/10

còn lại tự tính nhá

tui bận òi

a) 89-(73-x) = 20

=> 73+x =89-20

=> 73+x=69

=> x=69-73

=> x=-4

b) (x+7)-25=13

=> x+7=13+25

=> x+7=38

=> x=38-7

=> x=31

c) 98-(x+4)=20

=> x+4=98-20

=> x+4=78

=> x=78-4

=> x=73

d) 140:(x-8)=7

=> x-8=140:7

=> x-8=20

=> x=20+8

=> x=28

e) 4(x+41)=400

=> x+41=400:4

=> x+41=100

=> x=100-41

=> x=59

f) x-[42+(-28)]=-8

=> x-14=-8

=> x=-8+14

=> x=6

g) x+5=20-(12-7)

=> x+5=20-5

=> x+5=15

=> x=15-5

=> x=10

h) \(x-11=2.2^3+20:5\)

=> x-11=2.8+4

=> x-11=16+4

=> x-11=20

=> x=20+11

=> x=31

i) \(4\left(x-3\right)=7^2-1^3\)

=> 4(x-3)=49-1

=> 4(x-3)=48

=> x-3=48:4

=> x-3=12

=> x=12+3

=> x=15

a)

12 × 4 = 4 × 12

106 × 3 = 3 × 106

(17 × 5) × 2 = 17 × (5 × 2)

86 × 2 × 5 = 86 × (2 × 5)

b)

7 × 1 = 7

432 × 1 = 432

519 × 0 = 0

1 × 0 = 0

2 × 0 = 0

3 456 × 1 = 3 456