Question

Rezolvați prin metoda substituției vă rog dau coroană ​

Answer 1

a)

$\begin{cases}2x-3y=7 \\4x+4y=4 \end{cases}$

$4x+4y=4 \iff x+y=1 \iff y = 1 - x$

$2x-3(1-x)=7 \iff 2x-3+3x=7$

$5x = 10 \implies x = 2$

$y = 1-2 \implies y = -1$

$R: \bf x = 2; y = -1$

b)

$\begin{cases}2x+4y=2 \\4x+6y=0 \end{cases}$

$2x+4y=2 \iff x+2y=1 \iff x = 1-2y$

$4(1-2y)+6y=0 \iff 4-8y+6y=0$

$2y=4 \implies y = 2$

$x = 1 - 2 \cdot 2 = 1 - 4 \implies x = -3$

$R: \bf x = -3; y = 2$