39.(191 - 113) - 29.(191 - 113) = 39.78 - 29.78 = 78.(39 - 29) = 78.10 = 780

a ) x = 8 5 . b ) x = 11 5 . c ) x = 1 2 . d ) x = 1 2 .

a, 54 x 113 + 45 x 113 + 113

= 113 x ( 54+45+1)

= 113 x 100

= 11300

b, 3 x 7/10 + 7/10 x 5 + 2 x 14/20

= 7/10 + ( 3+5+2)

= 7/10 x 10

= 7

a,

= 113 x (54 + 45 + 1)

= 113 x 100

= 11300

b,

= 7/10 x (3 + 5 + 2)

= 7/10 x 10

= 7

a,  x - 1 2 = 36

ó  x - 1 2 = 6 2

ó x – 1 = 6

ó x = 7

Vậy x = 7

b,  7 x - 11 3 = 2 5 . 5 2 + 200

=> 7 x - 11 3 = 800 + 200

=> 7 x - 11 3 = 1000

=> 7 x - 11 3 = 10 3

=> 7x – 11 = 10

=> 7x = 21

=> x = 3

Vậy x = 3

c,  x 11 = x

=> x 11 - x = 0

=> x ( x 10 - 1 ) = 0

=>

d,  x 2 = 2 3 + 3 2 + 4 3

=>  x 2 = 81

=> x = 9

e,  2 x 3 3 2 = 48

=>  2 x 3 9 = 48

=>  2 x 3 = 48 . 9

=>  x 3 = 216

=>  x 3 = 6 3

=> x = 6

f,  2 x + 1 3 = 125

=> 2 x + 1 3 = 5 3

=> 2x + 1 = 5

=> 2x = 4

=> x = 2

a ) x = 21 55 ; b ) x = − 11 26 ; c ) x = 11 18 ; d ) x = 1

d ) x = − 1 ; e ) x = 11 7 ; f ) x = 20

1/

a)28+2x=35-(-13)

  28+2x=48

  2x=48-28

  x=20:2

  x=10

b)2(x+1)²=-7+15

  2(x+1)²=8

  (x+1)²=4

   x+1²=2²

   x+1=2

   x=1

c)(-25)-(x+5)=415+5(x-83)

   -25-5-x=415+5x-415

   -30-x=5x

   -30=x+5x=6x

   x=-30:6

   x=-5

d)|x-2|+(-7)=-3

   |x-2|=-3+7

   |x-2|=4

=>x-2=4 hoặc x-2=-4

=>x=6 hoặc x=-2

Vậy x=6 hoặc x=-2

thank nguyễn mạnh khôi

1.a,=(54+45+1).113

=100.113

=11300

b,=(3/7+8/14)+(4/9+10/18)

=1+1

=2

2.a,=13/10+1/3

=49/30

b,=12/9.(1/12+1/6)

=12/9.1/4

=1/3

c,=3/4.3/2

=9/8

d,=3/2-1/3

=7/6

1:tính bằng cách thuận tiện nhất:

a)54 x 113 + 45 x 113 + 113

= 54 x 113 + 45 x 113 + 113x1

=113 x(54+45+1)

= 113x100

=1300

 b)3/7 + 4/9 + 8/14 + 10/18

=(3/7+8/14)+(4/9+10/18)

=    1           + 1

=2

c. TH1:/-8/=8

=8+(-2).3

=8-6=2

TH2:/-8/=8

=-8+(-2).3

=-8.(-6)

=-48

d.-887.(113+457)+113(887-457)

=-887.570+113.430

=-505590+48590

=-457000

e.(16+39)+(158-16-39)

=55+103

=158

c, \(\left|-8\right|+\left(-2\right).3\) => \(8+\left(-6\right)\) = \(2\)

d, \(-887.\left(113+457\right)+113.\left(887-457\right)\)

=> \(\left(-887\right).113+\left(-887\right).457+113.887-113.\left(457\right)\)

=> \(\left[\left(-887\right).113+113.887\right]+\left[\left(-887\right).457-113.457\right]\)

=> \(\left[113.\left(887-887\right)\right]+\left[457.\cdot\left(-113-887\right)\right]\)

=> \(\left[113.0\right]+\left(457.-1000\right)\)

=> \(0+-457000=-457000\)

e, \(\left(16+39\right)+\left(158-16-39\right)\)

=> \(\left(16+39+158-16-39\right)\)

=> \(\left(16-16\right)+\left(39-39\right)+158\)

=> \(0+0+158=158\)