lozoya3013 lozoya3013

13-09-2020
Mathematics

contestada

2x + y = 10
x - 2y = -5
if (x,y) is the solution to the system of equations above, what is the value of 3x - y?

Respuesta :

Аноним Аноним

13-09-2020

Answer:

3x - y = 5

Step-by-step explanation:

2x + y = 10 | ×2

x - 2y = -5

4x + 2y = 20

x - 2y = -5

add

4x + x + 2y - 2y = 20 - 5

5x = 15

x = 15 : 5

x = 3

replace x

4(3) + 2y = 20

12 + 2y = 20

2y = 8

y = 8 : 2

y = 4

3x - y =

= 3(3) - 4

= 9 - 4

= 5

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