Question

1. a) 3(x+3)-5(x+1)=4(x+4)
b) 8(3x-2)=5(12-3x)+20x-19
c) 3(2x+5)-4(1+2x)=6(2x+3)+21
2. a 2x-3y=17 si 3x+2y=6
b. 3(x+4)+y=3 si x+2(y+5)=2
VA ROGGGGGG!!!!

Answer 1

Răspuns:

Explicație pas cu pas:

a) 3(x+3)-5(x+1)=4(x+4) <=>

3x+9-5x-5 = 4x+16  =>

-2x+4 = 4x+16  =>

4x+2x = 4-16  => 6x = -12 =>

x = -12:6 => x = -2

b) 8(3x-2)=5(12-3x)+20x-19 <=>

24x-16 = 60-15x +20x-19 <=>

24x-5x = 16+41 =>

19x = 57  => x = 57:19 => x = 3

c) 3(2x+5)-4(1+2x)=6(2x+3)+21 <=>

6x+15-4-8x = 12x+18+21 =>

-2x+11 = 12x +39  =>

12x+2x = 11-39  => 14x = -28  => x = -28 : 14 =>

x = -2

a) {2x-3y=17    I ·2

    {3x+2y=6    I ·3  =>

 

{4x-6y = 34

{9x+6y = 18

-----------------

13x = 52 => x = 52:13 => x = 4

4·4-6y = 34  => 6y = 16-34  => 6y = -18  =>

y = -18 :6 => y = -3

b) {3(x+4)+y=3

  { x+2(y+5)=2

<=> {3x+12 +y = 3

       {x+2y+10 = 2  <=>

{3x+y = -9   I·(-2)

{x+2y = -8  =>

{-6x-2y = 18

{x+2y = -8

---------------

-5x = 10  => x = 10:(-5) => x = -2

-2+2y = -8  => 2y = -8+2  => 2y = -6 =>

y = -6:2 => y = -3