Question

1)упростите:

-5/9(5,4m-1 4/5n)-6,4-(3/9+2,5n)

2) решите:

3/4(1/2x+2/3)= 3x +2 1/4;

6x/7= x-5/ 2.

3)решите №2;

(-12,6 * 1 1/9 +10,8) : 6 6/7 + 2 3/10.

зарание огромное спасибо :*

Answer 1

6x/7=x-5/2
12x=7x-35
12x-7x=-35
5x=-35
x=-7

Ответ: -7

 

 

3x/8+6/12=3x+7/4
12x+12/24=12x+7/4
x+1/2=12x+7/4
4x+4=24x+14
-20x=10
x=-2

Answer 2

1) -5/9*(5,4m-1 4/5n)-6.4-(3/9+2.5n) = -3m+n-6.4-3/9-2.5n = -3m-1.5n- 6 4/10-3/9 = 

= -3m-1.5n-64/10-3/9 = -3m-1.5n-576/90-30/90 = -3m-1.5n-606/90 =

= -3m-1.5n-202/45 

 

2) 3/4*(1/2х+2/3) = 3х+2 1/4

3/8х+1/2 = 3х+9/4

3/8х -3х = 9/4-1/2

3/8х - 2 8/8х = 9/4-2/4

-2 5/8х = 7/4

-21/8х = 7/4

х = 7/4:(-21/8)

х = 7/4*(-8/21)

х = -2/3

3/4*(1/2*(-2/3)+2/3) = 3*(-2/3)+2 1/4

3/4*(-1/3+2/3) = -2+2 1/4

3/4*1/3 = 1/4

Ответ: -2/3.

 

6х/7 = х-5/ 2

6х/7 = х/2-5/2

6х/7-х/2 = -5/2

12х/14-7х-14 = -5/2

5х/14 = -5/2

5х= -5/2:1/14

5х = -5/2*14

5х = -35

х = -35:5

х = -7

6*(-7)/7 = -7-5 /2

-42/7 = -12/2 = -6

Ответ: -7.

 

(-12,6*1 1/9+10,8):6 6/7+2 3/10 = (-12 6/10*10/9+10 8/10):48/7+23/10 =

= (-126/10*10/9+108/10)*7/48+23/10 = (-14+108/10)*7/48+23/10 = (-140/10+108/10)*7/48+23/10 = -32/10*7/48+23/10 = -14/30+23/10 = -14/30+69/30 = 55/30 = 11/6 = 1 5/6