a) 3m+n=9 2m-5n=-11 n=9-3m 2m-5(9-3m)=-11 n=9-3m 2m-45+15m=-11 n=9-3m 17m=34 m=2 n=9-3*2=3 b) 4a-2=b 3a+7b=1,5 4a=b+2 3a+7b=1,5 a=b/2+0,5 3(b/2+0,5)+7b=1,5 a=b/2+0,5 3b/2+1,5=1,5 a=b/2+0,5 3b=0 a=b/2+0,5 b=0 b=0 a=0,5 c) 5x=4-2y 4x+y=3 y=3-4x 5x+2(3-4x)=-4 y=3-4x 5x+6-8x=-4 y=3-4x -3x=-10 y=3-4x x=0,3 x=0,3 y=1,8 d) 6x-3y=9 x+5y=-9,5 x=-9,5-5y 6(-9,5-5y)-3y=9 x=-9,5-5y -57-30y-3y=9 x=-9,5-5y -33y=66 y=-2 x=0,5
a) 3m+n=9 2m-5n=-11 n=9-3m 2m-5(9-3m)=-11 2m-45+15m=-11 17m=34 m=2 n=9-3*2=3 b) 4a-2=b 3a+7b=1,5 3a+7(4a-2)=1,5 3a+28a-14=1,5 31a=15,5 a=1/2 b=4*(1/2)-2=0 c) 5x=4-2y 4x+y=3 y=3-4x 5x=4-2(3-4x) 5x=4-6+8x -3x=-2 x=2/3 y=3-4*(2/3)=1/3 d) 6x-3y=9 x+5y=-9,5 2x-y=3 y=2x-3 x+5(2x-3)=-9,5 x+10x-15=-9,5 11x=5,5 x=1/2 y=2*(1/2)-3=-2
