x+2y=-2 2x-y=1 x=-2-2y 2(-2-2y)-y=1 x=-2-2y -4-4y-y=1 x=-2-2y -5y=1+4 / :(-5) x=-2-2y y=-1 x=-2-2(-1) y=-1 x=-2 y=-1 b)x+4y=-2 3x-8y=10 x=-2-4y 3(-2-4y)=10 x=-2-4y -6-12y=10 x=-2-4y -12y=16 / : (-12) x=-2-4y y= -1,33 x=-2-4(-1,33) y= -1,33 x=7 y=-1,33 c)x-2y=3 -2x+y=0
a) x+2y=-2 / -2y 2x-y=1 x= -2-2y 2×(-2-2y) - y = 1 x =-2 -2y -4-4y -y =1/+4 x=-2 -2y -5y=5 / :(-5) x=-2 -2y y=-5 x= -2 -2×(-5) y=-5 x=-12 y=-5 b) x+4y=-2 / -4y 3x-8y=10 x=-2 - 4y 3×(-2 - 4y) - 8y = 10 x=-2 - 4y -6 - 12y - 8y = 10 x= -2 - 4y -20y = 16 /:(-20) x= -2 - 4y y = -0,8 x= -2 -4×(-0,8) y=-0,8 x= 1,2 y = -0,8 c) x-2y=3 /+ 2y -2x+y=0 x=3 + 2y -2×(3+2y)+y = 0 x=3 + 2y -6 -4y +y = 0 x=3 + 2y -3y = 6 x= 3 + 2y y = -2 x= 3 + 2×(-2) y = -2 x= -1 y = -2 d) 2x+y=9 / -2x 5x-4y=3 y=9 - 2x 5x - 4×(9 - 2x) = 3 y= 9-2x 5x-36+8x = 3 y = 9-2x 13x = 39 x= 3 y=9 - 2×3 x=3 y=3 e) 3x-2y=5 2x-y=4 / -2x 3x-2y =5 -y=4-2x 3x-2y=5 y=-4+2x 3x-2×(-4+2x)=5 y=-4+2x 3x+8-4x=5 y=-4+2x -x=-3 y=-4+2x x=3 y=-4+2×3 x=3 y=2
