1. 12x^2+16x-3=0
D=256+144=400
x1=(-16+20)/2=2
x2=(-16-20)/2=-18
3. x^2-3x=0
x(x-3)=0
x=0, x=3
4.2x^2-72=0
2x(x-36)=0
2x=0 x=36
x=0
5. 8x^2-5x-3=0
D=25+96=121
x1=5+11/2=8
x2=5-11/2=-3
6. x^2+3x-18=0
D=9+72=81
x1=-3+9/2=3
x2=-3-9/2=-6
7. 9y^2+12y+4=0
D=144-144=0
х=-12/18=-2/3