3)15y²-22y-37=0
D=b²-4ac=22²-4*15*(-37)=484+2220=2704=52²
y1=-b+√D/2a=22+52/30=37/15
y2=22-52/30=-1
4)5x²-6x+1=0
D=b²-4ac=36-4*5*1=36-20=16=4²
x1=-b+√D/2a=6+4/10=1
x2=6-4/10=2/10=1/5
5)4x²-36x+77=0
D=b²-4ac=1296-4*4*77=1296-1232=64=8²
x1=-b+√D/2a=36+8/8=44/8=11/2
x2=36-8/8=28/8=7/2
6)x²-22x-23=0
D=b²-4ac=484-4*1*(-23)=484+92=576=24²
x1=-b+√D/2a=22+24/2=46/2=23
x2=22-24/2=-1