a) {2x-2y=7 {4x+3y=21 b) {2x+3y=14{3x-2y=8 c) {½x-2y=8 {2x+5y=6 d) {½x-¾y=0 {⅔+1¼y=9 Pliska napiszcie

[latex]a)\ left { {{2x-2y=7 /*(-2)} atop {{4x+3y=21 }} ight.\ left { {{-4x+4y=-14} atop {{4x+3y=21 }} ight.\ -------\ 7y=7 /:7\ y=1\ \ 2x-2y=7\ 2x-2*1=7\ 2x=9 /:2\ x=4,5\ \ left { {{x=4,5} atop {y=1}} ight. [/latex] [latex]b)\ left { {{2x+3y=14 /*2} atop {3x-2y=8 /3}} ight. \ left { {{4x+6y=28} atop {9x-6y=24}} ight. \ -------\ 13x=52 /:13\ x=4\ \ 2x+3y=14\ 2*4+3y=14\ 3y=6 /:3\ y=2\ \ left { {{x=4} atop {y=2}} ight.[/latex] [latex]c)\ left { {{frac{1}{2}x-2y=8 /*(-4)} atop {2x+5y=6}} ight.\ left { {{-2x+8y=-32} atop {2x+5y=6}} ight.\ -------\ 13y=-26 /:13\ y=-2\ \ frac{1}{2}x-2y=8\ frac{1}{2}x-2*(-2)=8\ frac{1}{2}x=4 /*2\ x=8[/latex] [latex]d)\ left { {{frac{1}{2}x-frac{3}{4}y=0 /*5} atop {frac{2}{3}x+1frac{1}{4}y=9 /*3 }} ight. \ left { {{frac{1}{2}x-frac{15}{4}y=0} atop {frac{2}{3}x+frac{15}{4}y=9 }} ight. \ -------\ frac{27}{6}x=27 /*frac{6}{27}\ x=6\ \ frac{1}{2}x-frac{3}{4}y=0 \ frac{1}{2}*6-frac{3}{4}y=0 \ -frac{3}{4}y=3 /*(-frac{4}{3})\ y=-4\ \ left { {{x=6} atop {y=-4}} ight.[/latex] Liczę na najlepsze :)