Question

RESOLVA OS SISTEMAS:
2x + y - 4 = 0
x +2(x-y) = -1

Answer 1

2x + y = 4

x + 2x - 2y = -1

2x + y = 4 ---> * (2)

3x - 2y = -1

4x + 2y = 8

3x - 2y = -1

7x = 7

x = 7 : 7

x = 1

2x + y = 4

2 * 1 + y = 4

2 + y = 4

y = 4 - 2

y = 2

Answer 2

Primeiro devemos desenvolver os sistemas para poder aplicar o método da adição/substituição:

$\mathtt{2x + y-4 = 0} \\ \mathtt{2x + y = 4} \\ \\ \mathtt{x + 2~.~(x - y) = -1} \\ \mathtt{x + 2x - 2y = -1} \\ \mathtt{3x - 2y = -1} \\ \\ \mathtt{Agora~vamos~aplicar~adi\c{c}\~ao} \\ \\ \mathtt{2x + y = 4~~~~(2)} \\ \mathtt{3x - 2y = -1} \\ \\ \mathtt{Agora~efetuar~adi\c{c}\~ao} \\ \\ \mathtt{4x + 2y = 8} \\ \mathtt{3x - 2y =-1} \\ \mathtt{-------} \\ \mathtt{7x~~~~~~=7} \\ \mathtt{x = 7\div 7} \\ \mathtt{x = 1}$

$\mathtt{Substituir~x} \\ \\ \mathtt{2x + y = 4} \\ \mathtt{2~.~1 + y = 4} \\ \mathtt{2 + y = 4} \\ \mathtt{y = 4 - 2} \\ \mathtt{y = 2} \\ \\ \\ \boxed{\boxed{\mathtt{Resposta: ~~ x= 1~~~~~~y = 2}}}$