cw. 3
[tex]a)\\\\\left \{ {{3x-2y=-4} \atop {x+y=-3 /*2}} \right. \\\left \{ {{3x-2y=-4} \atop {2x+2y=-6}} \right. \\3x+2x-2y+2y=-4-6\\5x=-10 /:5\\x=-2\\-2+y=-3 /+2\\y=-1\\\\Odp. x=-2, y=-1[/tex]
[tex]b) \\\\\left \{ {{2x-3y=-4 /*2} \atop {3x-2y=-1 /*(-3)}} \right. \\\left \{ {{4x-6y=-8} \atop {-9x+6y=3}} \right. \\4x-9x=-8+3\\-5x=-5 /:(-5)\\x=1\\2*1-3y=-4\\2-3y=-4 /-2\\-3y=-6 /:(-3)\\y=2\\Odp. x=1, y=2[/tex]
[tex]c)\\\left \{ {{y-x=-13} \atop {\frac12x-\frac13y=5 /*2}} \right. \\\left \{ {{-x+y=-13} \atop {x-\frac23y=10}} \right. \\y-\frac23y=-13+10\\\frac13y=-3 /*3\\y=-9\\-9-x=-13 /+9\\-x=-4 /*(-1)\\x=4\\\\Odp. x=4, y=-9[/tex]
cw. 4
[tex]a)\\\left \{ {{x+2y=6 /*(-3)} \atop {3x+6y=13}} \right. \\\left \{ {{-3x-6y=-18} \atop {3x+6y=13}} \right. \\0=-18+13\\0 \neq -5\\\text{Brak rozwiazan}[/tex]
[tex]b)\\\left \{ {{-3x+4y=2 /*2} \atop {6x+8y=-4}} \right. \\\left \{ {{-6x+8y=4} \atop {6x+8y=-4}} \right. \\8y+8y=4-4\\16y=0 /:16\\y=0\\-3x+4*0=2\\-3x+0=2\\-3x=2 /:(-3)\\x=-\frac23\\Odp. x=-\frac23, y=0[/tex]
[tex]c)\\\left \{ {{2x-3y=5 /*2} \atop {-4x+6y=10}} \right. \\\left \{ {{4x-6y=10} \atop {-4x+6y=10}} \right. \\0 \neq 20\\\text{Brak rozwiazan}[/tex]
