6x^2+7x-3=0
Д=49+72=121
√Д=11
х1=(-7+11)/12=1/3
х2=(-7-11)/12=-1.5
___________________
20x^2+26x-6=0
Д=676+480=1156
√Д=34
х1=(-26+34)/40=8/40=0,2
х2=(-26-34)/40=-1.5
____________________
3x^2-19x-14=0
Д=361+168=529
√Д=23
х1=(19+23)/6=7
х2=(19-23)/6=2/3