Răspuns:
a)
[tex]\left \{ {{3x+5y=-9} \atop {y=-2x+1}} \right. =>\left \{ {{3x+5(-2x+1)=-9} \atop {y=-2x+1}} \right. =>\left \{ {{3x+-10x+5=-9} \atop {y=-2x+1}} \right. =>\left \{ {{-7x=-14} \atop {y=-2x+1}} \right. =>\left \{ {{x=2} \atop {y=-2*2+1}} \right. =>\left \{ {{x=2} \atop {y=-3} \right. \\[/tex]
b)
[tex]\left \{ {{3x+5y=-9} \atop {-2x-y=-1}} \right. \\\left \{ {{3x+5y=-9} \atop {-10x-5y=-5}} \right. \\3x-10x+5y-5y=-9-5\\-7x=-14\\x=2\\y=1-2x=1-4=-3[/tex]
