Question

rezolvati urmatorul sistem de ecuatii :{3x+4(y+2)=3 2(x+2)+2y=0​

Answer 1

3x+4(y+2)=3

2(x+2)+2y=0

3x+4y+8=3

2x+2y+4=0/×(-2)

3x+4y=-5

-4x-4y=-4×(-2)

adunam si obtinem

3x-4x+4y-4y=-5+8

-x=3

x=-3

acum inlocuim intro relatie pe x sa aflam y

3x+4y=-5

-9+4y=-5

4y=4

y=1

solutia sist este (-3;1)

Answer 2

$\it \begin{cases}\it 3x+4(y+2)=3\\ \\ \it 2(x+2)+2y=0\end{cases} \\ \\ \\ 2(x+2)+2y=0|_{:2} \Rightarrow x+2+y=0 \Rightarrow x=-(y+2)\ \ \ \ (*)\\ \\ 3x+4(y+2)=3 \stackrel{(*)}{\Longrightarrow}\ -3(y+2)+4(y+2)=3 \Rightarrow y+2=3 \Rightarrow y=1\\ \\ y=1\ \stackrel{(*)}{\Longrightarrow}\ x=-(1+2)\Rightarrow x=-3\\ \\ S=\{-3,\ 1\}$