a)x=4 b)y=7 c)x=42
a) -y-y=6 -2y=6/-2 y=-3 b) y=x+3 2x+x+3=9 y=x+3 3x=12/3 x=4 y=x+3 c) x-4x=15 y=4x -3x=15/-3 x=5 y=4x d) y=-2(y+7)-1 x=y+7 y=-2y+7-1 x=y+7 3y=6/3 x=y+7 y=2 e) -3x=2(1-x) y=1-x -3x=2-x y=1-x -2x=2/-2 y=1-x x=1 f) 5(4y-1)+6y=8 x=4y-1 20y-1+6y=8+1 x=4y-1 26y=9/26 x=4y-1 y=???
a ) x=-y x-y=6 x=-y -y-y=6 x=-y -2y=6 / : -2 x=-y y= -3 x= -3 y= -3 B) y=x+3 2x+y=9 y=x+3 2x+x+3 = 9 y=x+3 3x= 6 /:3 y=x+3 x = 2 y=2+3 x=2 y=5 x=2 C) x-y=15 y=4x x-4x=15 y=4x -3x = 15 /: (-3) y=4x x=-5 y=4*(-5) x=-5 y= -20 D) y=-2x-1 x=y+7 y=-2x - 1 x=-2x-1 + 7 y=-2x-1 3x=6 /: 3 y=-2x-1 x=2 y=-2*2-1 x=2 y=3 x=2 e) -3x=2y y=1-x -3x=2(1-x) y=1-x -3x= 2 -2x y=1-x x=-2 y=1+2 x=-2 y=3 F) 5x+6y=8 x=4y-1 5(4y-1) + 6y = 8 x=4y-1 20y - 5 + 6y = 8 x=4y-1 26y = 13 / : 26 x=4y-1 y=13/26 = ½ x=4 * ½ - 1 = 2 -1 = 1
