- x+y/2 + 5x-y/3=7x-3y/5 /*30 3/y+1=5/x-1 /*(y+1(x-1) -15x-15y+50x-10y=42x-18y 3(x-1)=5(y+1) 35x-42x=-18y+25y 3x-3=5y+5 -7x=7y /:7 3x-8=5y y=-x 3x-8=-5x →3x+5x=8 →8x=8 /:8 →x=8 y=-8 x=8 b) y-4=12x -1-2(x-2y)=-(x-2)²-(3-x)(x+3) y=12x+4 -1-2x+4y=-x²+4x-4-3x-9+x²+3x y=12x+4 -2x+4(12x+4)-4x+3x-3x=-13+1 →-6x+48x+16=-12 →54x=-12-16 →54x=-28 /:54 →x=-14/27 y=12*(-14/27)+4 →y=-6i2/9+4 →y=-2i2/9 x=-14/27 y=-2i2/9 c) 2y-(x-3)²=-48-(x-5)(5+x) y+x/2-x-y/4=o,75 /*4 2y-(x²-6x-9)=-48-(5x+x²-25-5x) 2y+2x-x+y=3 2y-x²+6x+9=-48+25 3y-x=3 2y+6x=-23-9 -x=3-3y /*(-1) 2y+6x=-32 x=3y-3 → 2y+6(3y-3)=-32 → 2y+18y-18=-32 → 20y=-32+18 → 20y=-14 /:20 → y=-0,7 x=3(-0,7)-3 → x=-2,1-3 →x=-5,1 x=-5,1 y=-0,7 d) 3[2(x-1/6y)-1]=-2y+6x 2[3(x-y)-9/4]=-6y+3x 3(2x-1/3y-1)=-2y+6x 2(3x-3y-9/4)=-6y+3x 6x-y-3=-2y+6x 6x-6y-4,5=16y+3x y=3 3x=4,5 /:3 y=3 x=1,5
