Question

por favor . qual a solução deste sistema? Estou com dificuldade
2y = 12+x
3x+8y=31

Answer 1

Tem!

■ 2y = 12 + x

■ 3x + 8y = 31 

3x + 4 (2y)  = 31

3x + 4 (12 + x) = 31 

3x + 48 + 4x = 31 

7x = 31 - 48 

7x = -17

■ x = -17/7

2y = 12 + x 

2y = 12 + (-17/7)

14y = 84 - 17

14y = 67

■ y = 67/14

Vamos a prova: 
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2(67/14) = 12 + (-17/7)

67/7  = 12 - 17/7 ↔ 67/7 = (84 - 17)/7 ↔ 67/7 = 67/7 → ok!
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3(-17/7) + 8(67/14) = 31

-51/7 + 268/7 = 31 ↔ (-51 + 268)/7 = 31 ↔ 217/7 = 31 ↔ 31 = 31 → ok!


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20/07/2016
Sepauto - SSRC
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Answer 2

2y = 12+x  ==> - x + 2y = 12
3x+8y=31
-x + 2y = 12(3)
3x+8y=31

-3x + 6y = 36
3x+8y=31     14y = 67 ==> y = 67/14
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2y = x + 12 ==> x = 2y - 12

x = 2.67 - 12 ==> x = 134- 168
        14                          14

x = - 34
        14                       

V = {( -34/14, 67/14)}