8.
[tex]a) \\\left \{ {{3x+4=2y-4} \atop {x+y=1-x}} \right. \\\left \{ {{3x+4=2y-4} \atop {y=1-2x}} \right. \\\left \{ {{3x+4=2(1-2x)-4} \atop {y=1-2x}} \right. \\\left \{ {{3x+4=2-4x-4} \atop {y=1-2x}} \right. \\\left \{ {{3x+4=-4x-2} \atop {y=1-2x}} \right. \\\left \{ {{3x+4x=-2-4} \atop {y=1-2x}} \right. \\\left \{ {{7x=-6 /:7} \atop {y=1-2x}} \right. \\\left \{ {{x=-\frac67} \atop {y=1-2*(-\frac67)}} \right. \\\left \{ {{x=-\frac67} \atop {y=1+1\frac57}} \right. \\[/tex]
[tex]\left \{ {{x=-\frac67} \atop {y=2\frac57}} \right.[/tex]
[tex]b)\\\left \{ {{6y+x+1=0} \atop {2y-6x+7=0}} \right. \\\left \{ {{x=-6y-1} \atop {2y-6(-6y-1)+7=0}} \right. \\\left \{ {{x=-6y-1} \atop {2y+36y+6+7=0}} \right. \\\left \{ {{x=-6y-1} \atop {38y=-13 /:38}} \right. \\\left \{ {{x=-6*(-\frac{13}{38})-\frac{38}{38}} \atop {y=-\frac{13}{38}}} \right. \\\left \{ {{x=\frac{40}{38}}} \atop {y=-\frac{13}{38}}} \right. \\\left \{ {{x=\frac{20}{18}} \atop {y=-\frac{13}{38}}} \right.[/tex]
[tex]c)\\\frac{x+10}2+y=\frac{y+5}2-3 /*2\\x+10+2y=y+5-6\\x=y-2y-1-10\\x=-y-11\\\\3-\frac{3x-2y}2=5+2y /*2\\6-(3x-2y)=10+4y\\6-3x+2y=10+4y\\-3x=10+4y-6-2y\\-3x=4+2y\\\\\left \{ {{\frac{x+10}2+y=\frac{y+5}2-3} \atop {3-\frac{3x-2y}2=5+2y}} \right. \\\left \{ {{x=-y-11} \atop {-3x=4+2y}} \right. \\\left \{ {{x=-y-11} \atop {-3(-y-11)=4+2y}} \right. \\\left \{ {{x=-y-11} \atop {3y+33=4+2y}} \right. \\\left \{ {{x=-y-11} \atop {3y-2y=4-33}} \right. \\\left \{ {{x=29-11} \atop {y=-29}} \right. \\[/tex]
[tex]\left \{ {{y=18} \atop {y=-29}} \right.[/tex]
9.
[tex]a) \\\left \{ {{3x-2y=5 /*2} \atop {-2x+\frac43y=-3 /*3}} \right. \\+\left \{ {{6x-4y=10} \atop {-6x+4y=-9}} \right. \\0\neq 1\\\text{Uklad sprzeczny}[/tex]
[tex]b) \\\left \{ {{7.5x-5y=6} \atop {2y-3x=-2.4}} \right. \\\left \{ {{-5y+7.5x=6 /*2} \atop {2y-3x=-2.4/*5}} \right. \\\left \{ {{-10y+15x=12} \atop {10y-15x=-12}} \right. \\0=0\\\text{Uklad nieoznaczony}[/tex]
[tex]c) \\\left \{ {{2x+3y=-\frac13 /*(-2)} \atop {4x-4\frac12y=6}} \right. \\\left \{ {{-4x-6y=\frac23} \atop {4x-4\frac12y=6}} \right. \\-6y-4\frac12y=\frac23+6\\-10\frac12y=6\frac23\\-\frac{21}2y=\frac{20}3 /*2\\-21y=\frac{40}3 /*(-\frac1{21})\\y=-\frac{40}{63}\\2x+3*(-\frac{40}{63})=-\frac13\\2x-\frac{120}{63}=-\frac13 /+\frac{120}{63}\\2x=-\frac{21}{63}+\frac{120}{63}\\2x=\frac{99}{63}\\2x=\frac{11}{7} /*\frac12\\x=\frac{11}{14}\\\text{Uklad oznaczony}[/tex]
