Question

x+2y=5
2x-3y=-4
VALENDO 27 PONTOS A CERTA

Answer 1

Por Substituição:


$\begin{cases}x+2y=5\\ 2x-3y=-4\end{cases}\\\\\\\\x+2y=5\to~~x=-2y+5\\\\\\\\2x-3y=-4\to~~2(-2y+5)-3y=-4\to~~ -4y+10-3y=-4\to\\\\ -4y-3y=-4-10\to~~ -7y=-14~(-1)\to~~7y=14\to~~y= \dfrac{14}{7} \to\\\\\large\boxed{y=2}\\\\\\\\x=-2y+5\to~~x=-2.2+5\to~~ x=-4+5\to~~\large\boxed{x=1}\\\\\\\\\\ \Large\boxed{\boxed{S=\{1~;~2\}}}$

Answer 2

Método da Adição:

x + 2y = 5       ( - 2)
2x - 3y = - 4

- 2x - 4y = - 10
  2x - 3y = - 4 (+)
      - 7y = - 14 ( - 1)
7y = 14
y = 14/7
y = 2

Substituir "y" e encontrar "x":

x + 2y = 5
x + 2.2 = 5
x + 4 = 5
x = 5 - 4
x = 1

Resp.: x = 1 e y = 2