a, 91 - 5 . ( 5 + x ) = 61

5 . (5+x)=91-61

5 . (5+x)=30

5+x=30:5

5+x=6

x=6-5

x=1

Bài 1. Tìm số tự nhiên x biết:

a, 91 - 5 . ( 5 + x ) = 61

5(5 + x) = 91 - 61

5(5 + x) = 30

5 + x = 30 : 5

5 + x = 6

x = 6-5

x= 1

b, ( x+ 34 ) - 50 = 56 : 2

( x + 34 ) - 50 = 28

x + 34 = 28 + 50

x + 34 = 68

x= 78 - 34

x = 44

Tk mk nha

Sao bạn bỏ một khoảng trống giữa các số 5 2 với 2 3v?

hả

a) 19 + (x - 23) = 50

x - 23 = 50 - 19

x - 23 = 31

=> x  = 31 + 23

     x = 54

b) (273 - x) - 140 = 34

(273 - x) = 34 + 140

(273 - x) = 174

x = 273 - 174

x = 99

c) 56 - (x - 14) = 22

x - 14 = 56 - 22

x - 14 = 34

x = 34 + 14

x = 48

d) 172 - (137 - x) = 93

137 - x = 172 - 93

137 - x = 79

x = 137 - 79

x = 58

e) 13. (x - 14) = 91

x - 14 = 91 : 13

x - 14 = 7

x = 14 + 7

x = 21

g) (13 - x).17 = 51

13 - x = 51 : 17

13 - x = 3

x = 13 - 3

x = 10

chúc bn học giỏi ^^ !

ok mk nha!! ! 5654645645767676576558578779769675634636457567687689978978978978766876765657886567567

1.19+(x-23)=50

<=>x-23=50-19

<=>x-23=31

<=>x=31+23

<=.x=54

vậy x=54

a,91-5(5+x)=61

=>25+5x=91-61=30

=>5x=30-25=5

=>x=1

b,\([\left(x+34\right)-50]\)x2=56

=>(x+34)-50=56:2=28

=>x+34=28+50=78

=>x=78-34=44.

c,1045-\([2015-\left(3x-24\right)]\)=5

=>2015-(3x-24)=1045-5=1040

=>3x-24=2015-1040=975

=>3x=975+24=999

=>x=999:3=333

d,\([195-\left(3x-27\right)]\)x39=4212

=>195-(3x-27)=4212:39=108

=>3x-27=195-108=87

=>3x=87+27=117

=>x=39

e,30-3(x-2)=18

=>30-3x+6=18

=>30-3x=18-6=12

=>3x=30-12=18

=>x=18:3=6

a) \(...\Rightarrow5\left(5+x\right)=91-61=30\)

\(\Rightarrow\left(5+x\right)=30:5=6\Rightarrow x=6-5=1\)

b) \(...\Rightarrow\left(x+34\right)-50=56:2=28\)

\(\Rightarrow\left(x+34\right)=28+50=78\Rightarrow x=78-34=44\)

c) \(...\Rightarrow2015-\left(3x-24\right)=1045-5=1040\)

\(\Rightarrow\left(3x-24\right)=2015-1040=975\)

\(\Rightarrow3x=975+24=999\Rightarrow x=999:3=333\)

d) \(...\Rightarrow195-\left(3x-27\right)=4212:39=108\)

\(\Rightarrow\left(3x-27\right)=195-108=87\)

\(\Rightarrow3x=87+27=114\Rightarrow x=114:3=38\)

e) \(...\Rightarrow3\left(x-2\right)=30-18=12\Rightarrow x-2=12:3=4\)

\(\Rightarrow x=4+2=6\)

Bài 1:

a. A = 125 . (-61) . (-2)³ . (-1)²⁴

= 125. (-8). (-61) . 1²⁴

= 125. 8. 61.1

= 1000. 61 = 61000

b. B = 136. (-47) + 36.47

= (-136).47 + 36.47

= 47. (-136 + 36)

= 47. (-100) = -4700

c. C = (-48).72 + 36.(-304)

= (-96).36 + 36. (-304)

= 36. (-96-304)

= 36. (-400) = -14400

d. D = 87.(13-18) - 13.(87 + 18)

= 87.13 - 87.18 - 13.87 - 13.18

= - 87.18 - 18.13

= - 18.(87+13)

= - 18.100 = -1800

Bài 2:

a. TH1: x - 2 = 0 => x = 2

TH2: 5-x = 0 => x = 5

b. |x| = 56 - 23 = 33 => x = cộng trừ 33

c. 3 - (17-x) = 289 - (36 + 289)

=> 3 - 17 + x = 289 - 289 - 36

=> -14 + x = -36

=> x = -36 - (-14) = -22

1. 

a. A = 125 . (-61) . (-2)³ . (-1)²⁴ 

= 125.(-61).(-8).1

= (-8.125).(-61)

= -1000.(-61)

= 61000

b. B = 136 . (-47) + 36 . 47 

=-136.47+36.47

=47(-136+36)

= 47.(-100)

= -4700

2. 

a. (x - 2) . (5 - x) = 0

=> x - 2 = 0 hoặc 5 - x = 0

=> x = 2 hoặc x = 5

b. 56 - lxl = 23 

=> |x| = 33

=> x = 33 hoặc x = -33

c. 3 - (17 - x) = 289 - (36 + 289) 

=> 3 - 17 + x = 289 - 36 - 289

=> -14 + x = -36

=> x = -22

dài quá bạn ơi

de giong nhau ma

hồi nãy mình copy lộn đó

a)

42.57 + 43.42 - 600

=42.(57+43)-600

=42.100-600

=4200-600

=3700

2².5²-64:2³

=4.25-64:8

=100-8

=92

a) 91 - 5(5+x) = 61

5(5+x) = 30

5+x=6

x=1

b) [(x+34) - 50]2 = 56

(x+34) - 50 = 28

x+34 = 78

x= 44

Tập hợp con của A có 2 phần tử:

{1;2} {1;3} {1;4}

(2;3} {2;4}

{3;4}

a) 91 - 5 . ( 5 + x ) = 61

          5 . ( 5 + x ) = 61  

          5 . ( 5 + x ) = 30

                 5 + x   = 30 : 5

                 5 + x   =    6

                       x   = 6 - 5

                       x   =   1.

b) [ ( x + 34 ) - 50 ] . 2 = 56

    [ ( x + 34 ) - 50 ]     = 56 : 2

    [ ( x + 34 ) - 50 ]     =   28

        x + 34                = 28 + 50

        x + 34                =     78

        x                        = 78 - 34

        x                        =    44.

2.Cho tập hợp A = { 1 ; 2 ; 3 ; 4 }

B = { 1 ; 2 }

C = { 1 ; 3 )

D = { 1 ; 4 }

E = { 2 ; 3 }

F = { 2 ; 4 }

a: \(=-9+\left\{-52:9\right\}=-9+\dfrac{-52}{9}=-\dfrac{133}{9}\)

b: \(=\dfrac{17}{7}+\left(\dfrac{-76}{63}\right):15\)

\(=\dfrac{17}{7}-\dfrac{76}{63}\cdot\dfrac{1}{15}=\dfrac{317}{135}\)

e: \(=\dfrac{-5}{13}\cdot\dfrac{7}{3}-\dfrac{2}{7}\cdot\dfrac{8}{13}+\dfrac{5}{13}\cdot\dfrac{1}{7}\)

\(=\dfrac{5}{13}\left(-\dfrac{7}{3}+\dfrac{1}{7}\right)-\dfrac{2}{7}\cdot\dfrac{8}{13}\)

\(=\dfrac{5}{13}\cdot\dfrac{-46}{21}-\dfrac{16}{91}=\dfrac{-278}{273}\)

Bài 2:

- \(\frac75\) + \(x\) = - \(\frac34\)

\(x\) = - \(\frac34+\frac75\)

\(x=-\frac{15}{20}\) + \(\frac{28}{20}\)

\(x\) = \(\frac{13}{20}\)

Vậy \(x=\frac{13}{20}\)

Bài 3:

- \(\frac74\) + \(\frac14:x\) = \(\frac32\)

\(\frac14:x\) = \(\frac32+\frac74\)

\(\frac14:x\) = \(\frac64+\frac74\)

\(\frac14:x=\frac{13}{4}\)

\(x=\frac14:\frac{13}{4}\)

\(x=\frac14\times\frac{4}{13}\)

\(x=\frac{1}{13}\)

Vậy \(x=\frac{1}{13}\)