Question

3x-y=7
x+2y=14
respuesta x= 4 : y= 5

por fas podrían ayudarme

5x-2y=5
2x+3y=21
respuesta:x=3 ; y=5

Answer 1

• 3x - y = 7

3x - 7 = y

• x + 2y = 14

x + 2(3x - 7) = 14

x + 6x - 14 = 14

7x = 14 + 14

7x = 28 → x = 4

• 3x - y = 7

3(4) - y = 7

12 - y = 7

12 - 7 = y → 5 = y

...

• 5x - 2y = 5

5x - 5 = 2y

(5x - 5)/2 = y

• 2x + 3y = 21

2x + 3[(5x - 5)/2] = 21

2x + (15x - 15)/2 = 21

(4x + 15x - 15)/2 = 21

19x - 15 = 21(2)

19x = 42 + 15

19x =57 → x = 3

• 2x + 3y = 21

2(3) + 3y = 21

6 + 3y = 21

3y = 21 -6

3y = 15 → y = 5