Question

ajutor la a si b ex 5 algebra​

Answer 1

Explicație pas cu pas:

a)

$\begin{cases}2x + y = 0 \\x - 3y = 7 \ \Big| \cdot(-2) \end{cases} \iff \begin{cases}2x + y = 0 \\-2x+6y = -14 \end{cases}$

$y + 6y = 0 - 14 \iff 7y = - 14$

$\implies \bf y = - 2$

$2x - 2 = 0 \iff 2x = 2$

$\implies \bf x = 1$

b)

$\begin{cases}4x - 2y = 0 \\x - y = - 1 \ \Big|\cdot ( - 2)\end{cases} \iff \begin{cases}4x - 2y = 0 \\ - 2x + 2y = 2 \end{cases}$

$4x - 2x = 0 + 2 \iff 2x = 2$

$\implies \bf x = 1$

$1 - y = - 1 \iff y = 1 + 1$

$\implies \bf y = 2$

Answer 2

$a) \: \begin{cases}2x + y = 0 \\ x - 3y = 7\end{cases} \\ y = - 2x\implies \: x -3 ( - 2x) = 7 \\ x + 6x = 7\implies \: 7x = 7\implies \: x = 1 \\ y = - 2x\implies \: y = - 2 \\ \\ \\ b) \: \begin{cases}4x - 2y = 0 \\ x - y = - 1\end{cases} \\ x = - 1 + y\implies 4( - 1 + y) - 2y = 0 \\ - 4 + 4y - 2y = 0 \\ - 4 + 2y = 0\implies 2y = 4\implies \: y = 2 \\ x - 2 = - 1\implies \: x = 1$