2) (2x+3)(x+1)=0
2x²+2x+3x+3=0
2x²+5x+3=0
a=2 b=5 c=3
D=b²-4ac=5²-4*2*3= 25-24=1
√D=√1=1
x₁=-b+√D/2a=-5+1/4=-1
x₂=-b-√D/2a=-5-1/4=-1.5
4) (5x-3)(2+3x)=0
10x+15x²-6-9x=0
15x²-x-6=0
a=15 b=-1 c=-6
D=b²-4ac=1-4*15*(-6)=1+360=361
√D=√361=19
x₁=-b+√D/2a=1+19/2*15=20/30=2/3
x₂=-b-√D/2a=1-19/2*15=-18/30=-3/5