1)3х^2-6х-1=0
2)а(3х+4)^2+в(3х+4)+с=0
3)-х^2+3х+4=0
4)ах^2+3вх+9х=0
5)х^2-6х-3=0
6)х^2-3х+11=0
7)12х^2-5х-2=0