a) (x+3)/2-(y-2)/3=2 /·6 (x+1)/4+(y+1)/3=4 /·12 {3(x+3)-2(y-2)=12 {3(x+1)+4(y+1)=48 {3x+9-2y+4=12 {3x+3+4y+4=48 {3x-2y =-1 /:2 {3x+4y=41 {1,5x-y=-0,5 {3x+4y=41 {y=1,5x+0,5 {3x+4(1,5x+0,5) =41 {3x+6x+2=41 {y=1,5x+0,5 {9x=39 {y=1,5x+0,5 {x=4⅓ {y=3/2 ·13/3 +½=39/6 + 3/6 =42/6=7 {x=4⅓ {y=7 b) (y-2x)/3-(3x-2y)/5=2 /·15 2(x-4y)/5-3(x-y)/2=1 /·10 {5(y-2x)-3(3x-2y)=30 {4(x-4y)-15(x-y)=10 {5y-10x-9x+6y=30 {4x-16y-15x+15y =10 {11y-19x=30 {-11x-y=10 {y=-11x-10 {11(-11x-10) -19x=30 {-121x-110 -19x =30 {y=-11x-10 {-140x =140 /: (-140) {y=-11x-10 {x=-1 {y=-11 ·(-1) -10 =11-10=1 {x=-1 {y=1
(x+3)/2-(y-2)/3=2 (x+1)/4+(y+1)/3=4 3(x+3)-2(y-2)=12 3(x+1)+4(y+1)=48 3x+9-2y+4=12 3x+3+4y+4=48 3x-2y=-1 3x+4y=41 -3x+2y=1 3x+4y=41 6y=42 y=7 3x-2y=-1 3x+4y=41 6x-4y=-2 3x+4y=41 6x+3x=39 9x=39 x=39/9 =13/3 x=13/3 y=7 ------------------------------------------------------------------------ (y-2x)/3-(3x-2y)/5=2 2(x-4y)/5-3(x-y)/2=1 5(y-2x)-3(3x-2y)=30 4(x-4y)-15(x-y)=10 5y-10x-9x+6y=30 4x-16y-15x+15y=10 11y-19x=30 -11x-y=10 11y-19x=30 -y-11x=10 11y-19x=30 -11y-121x=110 -19x-121x=140 -140x=140 x=-1 11y-19x=30 /*11 -y-11x=10 /*(-19) 121y-209x=330 19y+209x=-190 121y+19y =330-190 140y=140 y=1 x=-1 y=1