a)5x5+5x3+5x2-10x5

5x(5+3+2-10)

5x1=5

b)(24+6x5+6)-(12+6x3)

6x(4+5+1)-[6x(2+3)]

60-30=30

c)23+39+37+21+34+26

(23+37)+(39+21)+(34+26)

60+60+60=60x3=180

a=0

b=300

c=180

a)  5 x (5 + 3 + 2 - 10) = 5 x 0 = 0

b)  6 x (9 - 5) = 6 x 4 = 24

c)  (23 + 37) + (39 + 21) + (34 + 26) = 60 + 60 + 60 = 60 x 3 =180

`a) 48048 - 48048 : 24 - 24 x 58 `

` = 48048 - 2002- 1392`

` = 46046 - 1392`

` = 44654`

b) 10000 - ( 93120 : 24 - 24 x 57 ) 

` = 10000 -  ( 3880 - 1368)`

` = 10000 - 2512`

` = 7488`

c) 100798 - 9894 : 34 x 23 - 23 =

` = 100798  - 6693 -23`

` = 94082`

a: =48048-2002-1392=44654

b: =10000-3880+1368=7488

c: =100798-6693-23=94082

a)44654
b)7488
c)94082

a/ M = (71+x)-(-24+x)+(-35-x) = 71 + x + 24 - x - 35 - x = (71 + 24 - 35) - x = 95 - 35 - x = 60 - x

b/ N=x-34-[(15+x)-(23-x)] = x - 34 - (15 + x - 23 + x) = x - 34 - (-8 + 2x) = x - 34 + 8 - 2x = -26 - x

\(a,M=\left(71+x\right)-\left(-24+x\right)+\left(-35-x\right)\)

        \(=71+x+24-x-35-x\)

        \(=60-x\)

\(b,N=x-34-\left[\left(15+x\right)-\left(23-x\right)\right]\)

       \(=x-34-\left(15+x-23+x\right)\)

       \(=x-34-15-x+23-x\)

       \(=-26-x\)

a) M=(71+x)-(-24+x)+(-35-x)

      = 71+x-(-24)-x+(-35)-x

      = (-24+71)+(-35)+(x-x-x)

      = 47+(-35)+(-x)

      = 12+(-x)

      = 12-x

 Vậy M=12-x

\(A=\frac{34}{7.13}+\frac{51}{13.22}+\frac{85}{22.37}+\frac{68}{37.49}\)

\(=\frac{17.2}{7.13}+\frac{17.3}{13.22}+\frac{17.5}{22.37}+\frac{17.4}{37.49}\)

\(=17\left(\frac{2}{7.13}+\frac{3}{13.22}+\frac{5}{22.37}+\frac{4}{37.49}\right)\)

\(=\frac{17}{3}\left(\frac{6}{7.13}+\frac{9}{13.22}+\frac{15}{22.37}+\frac{12}{37.49}\right)\)

\(=\frac{17}{3}\left(\frac{1}{7}-\frac{1}{13}+\frac{1}{13}-\frac{1}{22}+...+\frac{1}{37}-\frac{1}{49}\right)\)

\(=\frac{17}{3}\left(\frac{1}{7}-\frac{1}{49}\right)\)\(=\frac{17}{3}.\frac{6}{49}=\frac{17.2}{49}=\frac{34}{49}\)

Có : \(\frac{17}{24}=\frac{34}{48}\)

Vì 48 < 49 => \(\frac{34}{48}>\frac{34}{49}\). Hay \(\frac{17}{24}>A\)

cảm ơn Văn B ? nha !

1a) -54 . 76 + 12 .(-76) + 76.(-34)

= (-54 - 12 - 34).76

= -100 . 76

= -176

b) 37.(63 - 24) - 63.(24 + 37)

= 37 . 63 - 37 . 24 - 63.24 - 63 . 37

= (37.63 - 63.37) - (37 + 63) . 24

= 0 - 100 . 24

= - 2400

2a) x + (-27) = -23 - x

=> x + x = -23 + 27

=> 2x = 4

=> x = 4 : 2

=> x = 2

b) xy + 2x - y = 15

=> x(y + 2) - y = 15

=> x(y + 2) - (y + 2) = 13

=> (x - 1)(y + 2) = 13 = 1 . 13 = 13 . 1

Lập bảng :

Vậy ...

a) ( 71 + x ) - ( -24 - x ) + ( -35 - x )

= 71 + x + 24 + x - 35 - x

= ( 71 + 24 - 35 ) + ( x + x - x )

= 60 + x

b) x - 34 - [( 15 + x ) - ( 23 - x )]

= x - 34 - ( 15 + x - 23 + x )

= x - 34 - ( 15 - 23 + x2 )

= x - 34 - ( - 8 + 2x )

= x - 34 + 8 - 2x

= x - 2x + 8 - 34

= -x - 26

c) ( -15 + |x| ) + ( -25 - |x| )

= -15 + |x| - 25 + |x|

= -15 - 25 + x + x

= -40 + x2

a)(71+x)-(-24-x)+(-35-x)

=>71+x+24+x-35-x

=>60+x

b)x-34-[(15+x)-(23-x)]

=>x-34-(15+x-23+x)

=>x-34-15-x+23-x

=-x-26

71 + ( 26 - 3 . x ) ; 5 = 75 

        ( 26 - 3x ) : 5 = 75 - 71 

         ( 26 - 3x ) : 5 = 4 

          26 - 3x = 4.5 

          26 - 3x = 20

               3x = 26 - 20

               3x = 6

                x = 6 : 3 

                x = 2

a/ (71+x) - [(-24) - x] + [(-35) - x ]=71+x+24+x-35-x=x+60

b/ x - 34 - [(15 + x) - (23 - x)]=x-34-15-x-23+x=x-72

c/ 26 - [(-x) + 126 - 13) + [(-113) + x]=26+x-126+13-113+x=2x-200=2(x-100)