Question

Tìm x :

a) 13 - 2 ( x + 1 ) = 7

b) 6x + 2 . 4 = 5^2 . 2

c) 420 + 65 . 4 = ( x + 175 ) : 5 + 30 

d) 32 . 12 : 2 = ( x + 70 ) : 14 - 40

e) 231 - ( x - 6 ) = 1339 : 13

f) 10 + 2x = 4^5 : 4

g) 70 - 5 ( x - 3 ) = 45

Answer 1

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

Answer 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

Answer 3

b)6x+2.4=5².2

6x+2=50

6x=48

x=8

c)420+65.4=(x+175):5+30

(x+175):5+30=680

(x+175):5=650

x+175=3250

x=3075

Answer 4

b,  6x + 8 = 25 . 2

6x + 8 = 50

6x = 50 - 8

6x = 42  

x = 42 : 6 

x = 7

c, 420 + 260 = (x + 175): 5 + 30

(x + 175) : 5 +30 = 680

(x + 175) : 5 = 650

x + 175 = 650 . 5

x + 175 = 3250

x = 3075 

Answer 5

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

b/ 6x + 2 . 4 = 5² . 2

6x + 2 . 4 = 25 . 2

6x + 8 = 50

6x = 50 - 8

6x = 42

x = 42 : 6

x = 7

c/ 420 + 65 . 4 = (x + 175) : 5 + 30

420 + 260 = (x + 175) : 5 + 30

680 = (x + 175) : 5 + 30

680 - 30 = (x + 175) : 5

650 = (x + 175) : 5

650 . 5 = x + 175

3250 = x + 175

3250 - 175 = x

3075 = x

=> x = 3075

d/ 32 . 12 : 2 = (x + 70) : 14 - 40

384 : 2 = (x + 70) : 14 - 40

192 = (x + 70) : 14 - 40

192 + 40 = (x + 70) : 14

232 = (x + 70) : 14

232 . 14 = x + 70

3248 = x + 70

3248 - 70 = x

3178 = x

=> x = 3178

e/ 231 - (x - 6) = 1339 : 13

231 - (x - 6) = 103

x - 6 = 231 - 103

x - 6 = 128

x = 128 + 6

x = 134

f/ 10 + 2x = 4⁵ . 4

10 + 2x = 4⁴

10 + 2x = 256

2x = 256 - 10

2x = 246

x = 246 : 2

x = 123

g/ 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