a: \(\Leftrightarrow5x-42=251\)

=>5x=293

hay x=293/5

b: \(\Leftrightarrow20-x=20\)

hay x=0

c: \(\Leftrightarrow x-4300-\dfrac{1}{50}=4250\)

\(\Leftrightarrow x=\dfrac{427501}{50}\)

d: =>(x+200):4=460-340=120

=>x+200=480

hay x=280

e: =>5+15(x+1)=500-480=20

=>15(x+1)=15

=>x+1=1

hay x=0

Câu a:

xem lại đề bài

Câu b:

5 2/8x - 1/9 = 4 3/5

42/8x - 1/9 = 23/5

21/4x = 23/5 + 1/9

21/4x = 207/45 + 5/45

21/4x = 212/45

x = 212/45: 21/4

x = 212/45 x 4/21

x = 848/945

Vậy: x = 848/945

Câu c:

45%x - 2/3x = 75%

9/20x - 2/3x = 3/4

x(9/20 - 2/3) = 3/4

x(27/60 - 40/60) = 3/4

x.(-13/60) = 3/4

x = 3/4 : (-13/60)

x = 3/4 x (-60/13)

x = - 45/13

Vậy x = - 45/13

4 . 120 + [45 : 9 +15 . (x + 1) = 500

480 + [45 : 9 +15 . (x + 1) = 500

45 : 9 +15 . (x + 1) = 500-480

45 : 9 +15 . (x + 1) = 20

5 +15 . (x + 1) = 20

15 . (x + 1) = 20-5

15 . (x + 1) = 15

x + 1=15:15

x + 1=1

x=1-1

x=0

= 0

tick cho mink nha

a) 25 - (3 * x - 4) - 2 = 18            b) 256 - ( x + 71 ) = 92         c) ( x - 45 ) - 320 = 0      

25 - (3 * x - 4) = 18 + 2                  x + 71 = 256 - 92                  x - 45 = 0 + 320

25 - (3 * x - 4) = 20                       x + 71 = 164                         x - 45 = 320

3 * x - 4 = 5                                 x = 164 - 71                          x = 320 + 45

3 * x = 5 + 4                                x = 93                                  x = 365

3 * x = 9

x = 9 : 3

x = 3

d) x : 45 = 346            e) 3270 : x = 15

x = 346 . 45                   x = 3270 : 15

x = 15570                      x = 218

nhớ ủng hộ mik nghen

Câu a:

C = -3/7 x 5/9 + 4/9 x -3/7 + 15/7

C = (-3/7 x 5/9 + 4/9 x -3/7) + 15/7

C = -3/7.(5/9 + 4/9) + 15/7

C = -3/7.1 + 15/7

C = -3/7 + 15/7

C = 12/7

Câu b:

E = 0,7 x 8/3 x 20 x 0,375 x 5/28

E = (0,7 x 20 x 5/28) x (8/3 x 0,375)

E = (14 x 5/28) x (3/3)

E = 5/2 x 1

E = 5/2

=>480 + [ 5 + 15 . (x + 1) = 500

15 . ( x + 1 )=500 - 480 - 5 = 15

x + 1 =15 : 15 =1

x =1 - 1

x = 0

vay x =0

k nha

Mọi người ơi, giúp em với ạ

a) \(\left(9^4.8+9^4.5\right):\left(9^2.\left(10-1\right)\right)\)

=\(9^4.13:9^3=13.9=117\)

b) 100-(75-25)=100-50=50

Giải:

a) \(2\dfrac{17}{20}-1\dfrac{15}{11}+6\dfrac{9}{20}:3\)

\(=\dfrac{57}{20}-\dfrac{26}{11}+\dfrac{129}{20}:3\) 

\(=\dfrac{107}{220}+\dfrac{43}{20}\)

\(=\dfrac{29}{11}\)

b) \(4\dfrac{3}{7}:\left(\dfrac{7}{5}.4\dfrac{3}{7}\right)\) 

\(=\dfrac{31}{7}:\left(\dfrac{7}{5}.\dfrac{31}{7}\right)\) 

\(=\dfrac{31}{7}:\dfrac{31}{5}\) 

\(=\dfrac{5}{7}\) 

c) \(\left(3\dfrac{2}{9}.\dfrac{15}{23}.1\dfrac{7}{29}\right):\dfrac{5}{23}\) 

\(=\left(\dfrac{29}{9}.\dfrac{15}{23}.\dfrac{36}{29}\right):\dfrac{5}{23}\) 

\(=\dfrac{60}{23}:\dfrac{5}{23}\) 

\(=12\)