Question

⇒ Método de substituição

e) {2x + y = 7
{5x - 2y = -5

f) {x - y = 4
{2x - 4y = 13

Answer 1

Resposta:

$\text{\sf Leia abaixo}$

Explicação passo-a-passo:

$\begin{cases}\sf 2x + y = 7\\\sf 5x - 2y = -5\end{cases}$

$\sf y = 7 - 2x$

$\sf 5x - 2(7 - 2x) = -5$

$\sf 5x - 14 + 4x = -5$

$\sf 9x = -5 + 14$

$\sf 9x = 9$

$\boxed{\boxed{\sf x = 1}}$

$\sf y = 7 - 2.(1)$

$\sf y = 7 - 2$

$\boxed{\boxed{\sf y = 5}}$

$\begin{cases}\sf x - y = 4\\\sf 2x - 4y = 13\end{cases}$

$\sf y = x - 4$

$\sf 2x - 4(x - 4) = 13$

$\sf 2x - 4x + 16 = 13$

$\sf -2x = 13 - 16$

$\sf -2x = -3$

$\boxed{\boxed{\sf x = \dfrac{3}{2}}}$

$\sf y = \dfrac{3}{2} - 4$

$\sf y = \dfrac{3 - 8}{2}$

$\boxed{\boxed{\sf y = -\dfrac{5}{2}}}$