8(7-4y)-7(4y+1)+5(8y-1)=19 56-32y-28y-7+40y-5-19=0 -20y+56-31=0 -20y+25=0 -20y=-25/:(-20) y=25/20=5/4 b)3(2x+1)-5(12x-7)+7(6x-1)=23 6x+3-60x+35+42x-7=23 -12x+31=23 -12x=23-31 -12x=-8/:(-12) x=8/12=2/3 c)0.2x+0.5x+5(5x-1)-2.7x=6.5 0,2x+0,5x+25x-5-2,7x=6,5 23x=6,5+5 23x=11,5/:23 x=0,5 d)0.3(0.4x-1.2)+0.36x=0.6 0,12x-0,36+0,36x=0,6 0,48x=0,96/:0,48 x=2 e)(3x-1) (2x+7)=6x²+31 6x²+21x-2x-7=6x²+31 19x=38/:19 x=2 f)3x²-(3x+2)(x-1)=8 3x²-3x²+3x-2x+2=8 x=8-2 x=6 g)9x+6-(3x-4)(x+2)=36-3x² 9x+6-3x²-6x+4x+8=36-3x² 7x+14=36 7x=22/:7 x=22/7=3 1/7 h)7(2x-5)-[5(7x-2)-2(5x-7)]=-72 14x-35-(35x-10-10x+14)=-72 14x-35-25x-4=-72 -11x=-72+39 -11x=-33/:(-11) x=3
8(7-4y)-7(4y+1)+5(8y-1)=19 56-32y-28y-7+40y-5=19 -32y-28y+40y=19+5-56 -20y=-32 y=-32:(-20) y=1,6 3(2x+1)-5(12x-7)+7(6x-1)=23 6x+3-60x+30+42x-7=23 6x-60x+42x=23+7-30-3 -2x=-3 x=-3:(-2) x=1,5 0.2x+0.5x+5(5x-1)-2.7x=6.5 0.2x+0.5x+25x-5-2,7x=6,5 0.2x+0.5x+25x-2,7x=6,5+5 23x=11,5 x=11,5:23 x=0,5 0.3(0.4x-1.2)+0.36x=0.6 0,12x-0,36+0.36x=0.6 0,12x+0.36x=0.6+0,36 0,48x=0,96 x=0,96:0,48 x=2 (3x-1) (2x+7)=6x²+31 6x²+21x-2x-7=6x²+31 6x²-6x²+21x-2x=31+7 19x=38 x=38:19 x=2 3x²-(3x+2)(x-1)=8 3x²-3x²+3x+2x-2=8 3x+2x=8+2 5x=10 x=10:5 x=2 9x+6-(3x-4)(x+2)=36-3x² 9x+6-3x²-3x-4x-8=36-3x² -3x²+3x²+9x-3x-4x=36-6+8 9x-3x-4x=38 2x=38 x=38:2 x=19 7(2x-5)-[5(7x-2)-2(5x-7)]=-72 14x-35-[35x-10-10x+14]=-72 14x-35-35x+10+10x-14=-72 14x-35x+10x=-72+35-10+14 -21x=-13 x=-21:(-13) x=1,6
