a) 2/3x - 0,2y = 3 |*3 1/3x + 0,4y = -1 |*(-6) 2x-0,6y = 9 -2x-2,4y = 6 _____________ -3y = 15 |: (-3) y = -5 2x-0,6*(-5) = 9 2x+3 = 9 2x = 6 |:2 x = 3 y = -5 b) 0,3x-0,4y = 1,7 0,5x+0,2y = 1,1 |*2 0,3x-0,4y = 1,7 x+0,4y = 2,2 ___________ 1,3x = 3,9 |: 1,3 x = 3 3+0,4y = 2,2 0,4y = -0,8 |:0,4 y = -2 x = 3 c) 0,05x + 0,04y = -4 | *(-50) -3x+2y = 20 -2,5x-2y = 200 -3x+2y = 20 ____________ -5,5x = 220 | :(-5,5) x = -40 -3*(-40)+2y = 20 120+2y=20 2y = -100 |:2 y = -50 x = -40 e) 1/3(x+1)-1/2(y-1) = 0 3/4x(x+2)-1/2(y+1) = 1 1/3x+1/3-1/2y+1/2 = 0 |*6 3/4x+6/4-1/2y-1/2 = 1 |*4 2x+2-3y+3 = 0 3x+6-2y-2= 4 2x-3y = -5 3x-2y = 0 2x-3y = -5 2y = 3x |:2 2x-3y = -5 y = 1,5x 2x-3*1,5x = -5 2x-4,5x = -5 -2,5x = -5 |:(-2,5) x = 2 y = 1,5*2 = 3 f) x+2 / 2 - y-2 / 4 = 3 |*4 x-2 / 2 - 3y+1 / 7 = 0 |*14 2x+4-y+2 = 12 7x-14-6y-2 = 0 2x-y = 6 |*(-6) 7x-6y = 6 -12x+6y = -36 7x-6y = 6 ______________ -5x = -30 |:(-5) x = 6 2*6-y = 6 12-y = 6 -y = -6 |*(-1) y = 6 x = 6 g) x+6 / 3 + 3y+1 / 2 = 5 |*6 y+1 / 2 + x+5/8 = 2 |*(16) 2x+12+9y+3 = 30 -8y-8-2x-10 = -32 2x+9y = 15 -2x-8y = 14 __________ y = 1 2x-9 = 15 2x = 6 |: 2 x = 3 y = 1 h) x+1-y = -2 x - (y+1/5) = 2 | *(-5) x+1-y = -2 -5x+y+1 = -10 x-y = -3 -5x+y = -11 ___________ -4x = -14 |:(-4) x = -14/4 = 3,5 -3,5-y = -3 -y = -3-3,5 -y = -6,5 |*(-1) y = 6,5 x= 3,5
