Question

(3x+20y=60
(20x-5y=15

Answer 1

Olá.

Vamos resolver pelo método de adição...

3x + 20y = 60 m (1)

20x - 5y = 15 m (4)

3x + 20y = 60

80x - 20y = 60

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80x + 3x = 60 + 60

83x = 60 + 60

83x = 120

x = 120/83

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20x - 5y = 15

20(120/3) - 5y = 15

20/1 • 120/83 - 5y = 15

(20•120)/(83•1) - 5y = 15

2 400 / 83 - 5y = 15

-5y = 15 - 2 400 / 83

-5y = - 1 155/83

y = 1 155/83 ÷ 5

y = 231 / 83

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S ( 120/83 ; 231/83 )