98216=7814+X+2580

X      =98216-7814-2580

X     =87822

CHO MK NHA

K CHO MK NHA

98216 = 7814 +x + 2580

                       x=98216-7814-2580

                       x=87822

98216=7814+x+2580

7814+x+2580=98216

X+(7814+2580)=98216

X+10394=98216

X=98216-10394

X=87822

Tích nha

\(\frac{31}{53}.\frac{17}{28}+\frac{31}{28}.\frac{11}{53}\)

\(=\frac{31}{53}.\frac{17}{28}+\frac{11}{28}.\frac{31}{53}\)

\(=\frac{31}{53}.\left(\frac{17}{28}+\frac{11}{28}\right)\)

\(=\frac{31}{53}.1\)

\(=\frac{31}{53}\)

\(\frac{31}{53}\times\frac{17}{28}+\frac{31}{28}\times\frac{11}{53}\)

\(=\frac{31}{53}\times\frac{17}{28}+\frac{31}{53}\times\frac{11}{28}\)

\(=\frac{31}{53}\times\left(\frac{17}{28}+\frac{11}{28}\right)\)

\(=\frac{31}{53}\times1\)

\(=\frac{31}{53}\)

\(\frac{31}{53}.\frac{17}{28}+\frac{31}{28}.\frac{11}{53}=\frac{31}{53}.\frac{17}{28}+\frac{31}{53}.\frac{11}{28}\)

 \(=\frac{31}{53}.\left(\frac{17}{28}+\frac{11}{28}\right)=\frac{31}{53}.1=\frac{31}{53}.\)

a ) 13 x X + 15 = 106

      13 x X        = 106 - 15

      13 x X        =  91

              X        = 91 : 13

              X        = 7  

b ) 19 x X + 53 x X +28 x X = 700

      X x ( 19 + 53 + 28 )        = 700

      X                                    = 700 : 100

      X                                    = 7

~~~ Hok tốt ~~~

Giải :

a ) 13 * X +15 = 106

 => 13 * X = 106 - 15 = 91

=> X = 91 : 13 = 7

Vậy X = 7

b ) 19 * X + 53 * X +28 * X = 700

 = X * ( 19 + 53 + 28 ) = 700

=> X * 100 = 700

=> X = 700 : 100

=> X = 7

Vậy X = 7

Học tốt !!!!!!!!!!!!!!!!!!!

( x + 1 ) + ( x + 4 ) + ( x + 7 ) + ( x + 10) + ..........+ ( x + 28 ) = 155

10x + ( 1 + 4 + 7 + ... + 28 )    = 155

10x + 145                              = 155

10x                                          = 155 - 145

10x                                          = 10

x                                              = 10 : 10

Vậy x = 1

\(a,\left[x+1\right]+\left[x+4\right]+\left[x+7\right]+\left[x+10\right]+...+\left[x+28\right]=155\)

\(\Leftrightarrow x+1+x+4+x+7+x+10+...+x+28=155\)

\(\Leftrightarrow(x+x+x+...+x)+(1+4+7+...+28)=155\)

\(\Leftrightarrow10x+145=155\)

\(\Leftrightarrow10x=155-145\)

\(\Leftrightarrow10x=10\)

\(\Leftrightarrow x=1\)

\(b)(x\times0,25+1999)\times2000=(53+1999)\times2000\)

\(\Leftrightarrow(x\times0,25+1999)\times2000=4104000\)

\(\Leftrightarrow(x\times0,25+1999)=4104000:2000\)

\(\Leftrightarrow(x\times0,25+1999)=2052\)

\(\Leftrightarrow x\times0,25=2052-1999\)

\(\Leftrightarrow x\times0,25=53\)

\(\Leftrightarrow x=53:0,25=212\)

Câu c tự làm

còn câu c nữa giúp mình với đi các bạn.

a) x + 25 = 53

        x = 53 - 25

        x = 28 

b) x - 56 = 28

       x = 28 + 56

       x = 84

c) 56 - x = 17

      x = 56 - 17 

      x = 39

d) 22 - x = 16

       x = 22 - 16 

       x = 6 

x + 25 = 53

       x= 53 - 25

       x =  28

x - 56 = 28

       x = 28 + 56 

       x = 84

56 - x = 17 

       x = 56 - 17

        x = 39

22 - x = 16

       x = 22 - 16

        x = 6

\(2b,\)\(54\times47-47\times53-20-27.\)

\(=47\times54-47\times53-47\)

\(=47\times\left(54-53-1\right)\)

\(=47\times0=0\)

\(2c,\)\(10000-47\times72-47\times28\)

\(=100\times100-47\times\left(72+28\right)\)

\(=100\times100-47\times100\)

\(=100\times\left(100-47\right)\)

\(=100\times53=5300\)

2b

54 x 47 - 47 x 53 - 20 - 27 = 47 x ( 54 - 53 ) - 20 - 27 = 47 - 20 - 27 = 47 - ( 20 + 27 ) = 47 - 47 = 0

2c

10000 - 47 x 72 - 47 x 28 = 10000 - 47 x ( 72 - 28 ) = 10000 - 47 x 44 = 10000 - 2068 = 7932

A.35 x 34 + 35 x 38 + 65 x 75 + 65 x 45

Câu này không tính hợp lí được

B. 12x 53 + 53 x 172 - 53 x 84

= 53 x (12 + 172 - 84)

= 53 x 100

= 5300

C. 36 x 28 + 36 x 82 + 64 x 69 + 64 x 41

= 36 x (28+82) + 64 x (69+41)

= 36 x 110 + 64 x 110

= (36+64) x 110

= 100 x 110

= 11 000

D. A = 1+2+3+...+100

= (1+ 100) x 50

= 101 x 50

= 5050

E. B =17+19+...+101+103

= (103 +17) x [(103 - 17):2 + 1]

= 120 x 44

=5280

G. D= 3x (12+13+14+15) + 3x(8+7+6+5)

= 3 x (5+6+7+8+12+13+14+15)

= 3 x (20 x 4)

= 3 x 80

=240

a) 10320

b) 5300

c) 11000

d) 5050

e) 2460

g)  240