Question

Dintre perechile urmatoare (2;-7),(2;-1),(-2;1) solutie a sistemului {2x+y=-3
{5x-3y=-13 este ......

Answer 1

{2x+y=-3 |x3 ⇒{6x+3y=-9    adunand
{5x-3y=-13  ⇒{ 5x-3y=-13

11x=-22 ⇒x=-2
2x+y=-3 ⇒-4+y=-3 ⇒y=1
perechea este (-2,1)

Answer 2

[tex] \left \{ {{2x+y=-3|*(3)=\ \textgreater \ 6x+3y=-9} \atop {5x-3y=-13|*(+1)=\ \textgreater \ 5x-3y=-13}} \right. \\\\ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~------\\ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~11x=-22=\ \textgreater \ x=-2\\\\ 2*(-2)+y=-3=\ \textgreater \ -4+y=-3=\ \textgreater \ y=-3+4=\ \textgreater \ y=1\\\\\\ Proba:-4+1=-3(corect)\\ -10-3=-13(corect)[/tex]

Raspuns:c)(-2,1)

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