15720 – y=51784 : 8 
15720 – y= 6473
y=9247

15729-y=6473

y=15729-6473

y=9256

15720 – y = 51784 : 8 
15720 – y = 6473
 y = 9247

a)\(162:y+216:y=6\)

⇔\(\left(162+216\right):y=6\)

⇔\(378:y=6\)

⇔\(y=63\)

b)\(602:y+123.2=253\)

⇔\(602:y+246=253\)

⇔\(602:y=7\)

⇔\(y=86\)

c)\(8\left(15720-y\right)=51784\)

⇔\(125760-8y=51784\)

⇔\(8y=73976\)

⇔\(y=9247\)

15712-x=51784:8=6473

x=15712-6473=9239

Vậy x= 9239

125696 - 8x = 51784
              8x = 125696 - 51784 
               8x = 73912
                   x = 73912 : 8

                    x = 9239
 

\(8\times\left(15712-x\right)=51784\)

              \(15712-x=51784:8\)

              \(15712-x=6473\)

                                \(x=15712-6473\)

                                \(x=9239\)

=> x . ( 2 + 3 + 4 + 5 + 6 ) = x . 9 + 9999

=> x . 20 = x . 9 + 9999

=> x . 11 = 9999 ( cùng bớt x + 9 )

=> x = 9999 : 11

=> 909

  2x + 3x + 4x + 20x + 6x = 9x + 9999

           35x - 9x                = 9999

                 26x                 = 9999

                     x                 = 9999 / 26

Vậy : x = 9999 / 26

X x 2 + X x 3 + X x4 + X x5 + X x 6 = X x 9 + 9999

                            X x (2+3+4+5+6) = X x 9 +9999

                            X x 20                 = X x 9 +9999

                            X x 11 + X x 9      = X x 9 +9999

(bỏ  X x 9)             X x 11                  =           9999

                            X                         =  9999 : 11

                            X                         = 909

a ) 4⁵ . 4 . 4⁷ = 4⁵ . 4¹ . 4⁷ = 4¹³

b ) 4 . 4³ . 4⁵ . 4⁶ = 4¹ . 4³ . 4⁵ . 4⁶ = 4¹⁵

c ) x . x³ . x⁴ = x¹ . x³ . x⁴ = x⁸

d ) x⁵ . x⁴ . x⁷ . x⁶ = x²²

\(x\times2+x\times4+x\times6+...+x\times18+x\times20=440\)

\(\Rightarrow x\times\left(2+4+6+...+18+20\right)=440\)

\(\Rightarrow x\times110=440\)

\(\Rightarrow x=440\div110\)

\(\Rightarrow x=4\)

Vậy : \(x=4\)

x*2+x*4+x*6+.....+x*18+x*20=440

x*(2+4+6+...+18+20)=440

Có

4-2=6-4=...=20-18=2

số liền trước hơn số liền sau 2 đơn vị 

SSH là :(20-2):2+1=10

tổng là : (20+2)*10:2=110

thay vào ta có :

x*110=440

x=440 : 110

x=4

vậy x=4

2x+4x+6x+...+18x+20x=440

x*(2+4+6+...+18+20)=440

\(\frac{\left(20+2\right)\times10x}{2}=440\)

22*10x=880

220x=880

x=4

Vậy x=4

mk làm hơi tắt. b thông cảm

\(9x-5x+3x=56\)

<=>  \(7x=56\)

<=> \(x=8\)

Vậy...

\(9x-x+3x=165\)

<=> \(11x=165\)

<=> \(x=15\)

Vậy....

\(7x+8x-x=168\)

<=> \(14x=168\)

<=> \(x=12\)

Vậy...

\(\frac{5}{8}x-\frac{1}{3}x-\frac{1}{6}x=15\)

<=> \(\frac{1}{8}x=15\)

<=> \(x=120\)

Vậy...

Dấu . là dấu nhân nha

---

a, 9 . x - 5 . x + 3 . x = 56

x . (9 - 5 + 3) = 56

x . 7 = 56

x = 56 : 7

x = 8

b, 9 . x - x + 3 . x = 165

x . (9 - 1 + 3) = 165

x . 11 = 165

x = 165 : 11

x = 15

c, 7 . x + 8 . x - x = 168

x . (7 + 8 - 1) = 168

x . 14 = 168

x = 168 : 14

x = 12

d, 5/8 . x - 1/3 . x - 1/6 . x = 15

x . (5/8 - 1/3 - 1/6) = 15

x . 1/8 = 15

x = 15 : 1/8

x = 120

1.53x201=10653

2.

a)4 xX-15x4=6x15+X

<=>4x-60=90+x

<=>4x-x=60+90

<=>3x=150

<=>x=50

b(102+28-2x):20-5=1

<=>(130-2x):20=6

<=>130-2x=120

<=>2x=10

<=>x=5

c)1999x-x=1999+1997+1999

<=>1998x=5995

<=>\(x\approx3\)

d)105-5x=150:15

<=>105-5x=10

<=>5x=95

<=>x=19

e)(x+1)+(x+2)+(x+3)+...+(x+6)=78

<=>6x+21=78

<=>6x=57

<=>x=9,5

1) 53x201=53x200+53=10600+53=10653

2a)

4x-15x4=6x15+x

4x-60=90+x

4x-x=90+60

3x=150

x=50

b) x=5

c) x=3

d)x=19

e) x=9,5

các bạn ơi 4x và 3x là j vậy ??