a) -x+y=5 x+y=5 2y=10 /2 y=5 y=5 x+5=5 y=5 x=5-5 y=5 x=0 b) x-2y=4 -x+3y=0 y=4 x-2*4=4 y=4 x-8=4 y=4 x=12 c) 3u+2v=2 /*-2 5u+4v=6 -6u-4v=-4 5u+4v=6 u=2 3*2+2v=2 u=2 6+2v=2 u=2 2v=-3 / :2 u=2 v= -1,5 d) x-3y=5 3x+y=-5 /*3 x-3y=5 9x+3y=-15 10x=-10 /:10 x=-1 x=-1 -1*3+y=-5 x=-1 -3+y=-5 x=-1 y=-2
a) - x+y = 5 x + y = 5 ........... 2y=10/2 y=5 x + y = 5 x=5-y x=5-5 x=0 b) x - 2y = 4 - x + 3y = 0 .............. y=4 x - 2y = 4 x=4+2y x=4+2×4 x=4+8 x=12 c) 3u + 2v = 2/×(-2) 5u + 4v = 6 -6u-4v=-4 5u + 4v = 6 .......... -u=2 u=-2 3u + 2v = 2 2v=2-3u 2v=2-3×(-2) 2v=2+6 2v=8/÷2 v=4 d) x - 3y = 5/×(-3) y + 3x = -5 9y-3x=-15 y + 3x = -5 .............. 10y=-20/÷ 10 y=-2 x - 3y = 5 x=5+3y x=5+3×(-2) x=5-6 x=-1
-x+y=5 a x+y=5 y+y=5+5 2y=10 y=2 x+y=5 x+2=5 x=5-2 x=3 x=3 y=2 b x-2y=4 -x+3y=0 -2y+3y=4 y=4 x-2y=4 x-2×4=4 x-8=4 x=4+8 x=12 x=12 y=4 c 3u+2v=2 } -2 5u+4v=6 -6u-4v=-4 5u+4v=6 -6u+5u=-4+6 -u=2 }-1 u=-2 3×{-2}+2v=2 -6+2v=2 2v=2+6 2v=8 v=4 u=-2 v=4 d x-3y=5 y+3x=-5 x-3y=5 }-3 3x+y=-5 -3x+9y=-15 3x+y=-5 9y+y=-15-5 10y=-20 y=-2 x-3y=5 x-3×{-2}=5 x+6=5 x=5-6 x=-1 x=-1 y=-2
