\(707:\left[\left(2^x-5\right)+74\right]=16-9\)

\(707:\left(2^x-5+74\right)=7\)

\(2^x+69=707:7\)

\(2^x+69=101\)

\(2^x=32\)

\(2^x=2^5\)

\(x=5\)

x = 5 

a)

 \(x-\dfrac{5}{7}=\dfrac{1}{9}\\ x=\dfrac{1}{9}+\dfrac{5}{7}\\ x=\dfrac{52}{63}\)

b 

\(\dfrac{3}{10}-\left(x-5\right)=\dfrac{2}{15}\\ \left(x-5\right)=\dfrac{3}{10}-\dfrac{2}{15}\\ x-5=6\\ x=6+5\\ x=11\)

a) x -5/7 =1/9

            x =1/9 + 5/7

            x =52/63

b)3/10 - (x-5) = 2/15

   3/10 - x + 5 = 2/15

   53/10 -x = 2/15

              x = 53/10 -2/15

              x =31/6

a, 15/35 + 16/28

= 1 

b, 2 + 1 5/7

= 2 + 12/7

= 26/7 

c, 121212/363636 + 125/1000

= 1/3 + 1/8

= 11/24

a, =1

b,26/7

c,11/24

a, 15/35 + 16/28

= 1 

b, 2 + 1 5/7

= 2 + 12/7

= 26/7 

c, 121212/363636 + 125/1000

= 1/3 + 1/8

= 11/24

a, = 1 

b, = 26/7

c, = 11/24

(X-1)10=(X-1)5

[(X-1)⁵]²=(X-1)5

(X-1)²=0

(x-1) . (x-1) = 0

TH1: x-1=0 => x=1

Vậy x=1

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Bài 4 :

a] 28 . 62 - 28 . 57

= 28 . ( 62 - 57 )

= 28 . 5

= 140

b] 2 . 14 . 47 + 7 . 53 . 4

= 28 . 47 + 7 . 53 . 4 

= 1316 + 7 . 53 . 4 

= 1316 + 371 .4

= 1316 + 1484

= 2800

c] 2 . 13 . 7 - 17 . 3 . 3 + + 13 . 26 - 17 . 11

= 26 . 7 - 17 . 3 . 3 + 13 . 26 - 17 .11

= 182 - 17 . 3 . 3 + 13 . 26 - 17 . 11

= 182 - 51 . 3 + 338 - 187

= 182 - 153 + 338 - 187

= 29 + 338 - 187

= 367 - 187

= 180

A = 1 + 5¹ + 5² + 5³ +.......+ 5⁹⁹ + 5¹⁰⁰ + 5¹⁰¹

A = (1 + 5 + 5²) + 5³.(1+5+5²) + .......+5⁹⁹.(1+5+5²)

A = (1 + 5 + 25) + 5³.(1 + 5 + 25) +.......+ 5⁹⁹.(1 + 5 + 25)

A = 31 + 5³ .31 +.......+5⁹⁹.31

A = 31 .(5³ + 5⁶ +........+5⁹⁹)

vì 31 .(5³ + 5⁶ +........+5⁹⁹) ⋮ 31

vậy A ⋮ 31

\(=\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{4}+...+\dfrac{1}{9}-\dfrac{1}{10}=\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{10}=1-\dfrac{1}{10}=\dfrac{9}{10}\)

Giúp với

`a+b=10`

`a+5a=34`

`=> 6a=34`

`=> a=34:6`

`a=17/3`

Vậy `a=17/3`

Vậy `b=10-17/3=13/3`

a+b=10 và a+5a=34

a+5a=34        Thay a=\(\dfrac{17}{3}\) ta có 

1a+5a=34       \(\dfrac{17}{3}\)+b=10

a.(1+5)=34             b=10-\(\dfrac{17}{3}\)

a.6=34                    b=\(\dfrac{13}{3}\)

   a=34:6

   a=\(\dfrac{17}{3}\)

Vậy a=\(\dfrac{17}{3}\)    b=\(\dfrac{13}{3}\)

`45+43+(-215)+(-25)`

`=45+43-215-25`

`=(45-215-25)+43`

`=-195+43`

`=-152`

45 + 43 + ( -215 ) + ( -25 )

= = 88 - 215 - 25

= -152