Question

vă rog frumos sisteme de ecuații ​

Answer 1

$\begin{cases} 6(x+3-y)-7(-x+1)=11(x+3)\\15(2-x-3y)+4(2+3y)=4+5x \end{cases}$

$\begin{cases} 6x+18-6y+7x-7=11x+33\\30-15x-45y+8+12y=4+5x \end{cases}$

$\begin{cases} 13x-6y-11x=33 - 11\\-15x-33y-5x=4-38 \end{cases}$

$\begin{cases} 2x-6y=22 \ \Big|\cdot 10 \\-20x-33y=-34 \end{cases}$

$\begin{cases} 20x-60y=220 \\-20x-33y=-34 \end{cases}$

$-60y-33y = 440-34 \iff -93y = 186$

$y = 186 \: ( - 93) \implies y = - 2$

$2x-6( - 2)=22 \iff 2x = 22 - 12$

$2x = 10 \implies x = 5$

$\implies S = \bigg\{(5; - 2)\bigg\}$