Răspuns:
Explicație pas cu pas:
1.
x²-8x+20=0
E=x1x2-3(x1+x2)
x1+x2=8
x1x2=20 E=20-3×8=20-24=-4
2.
a)3x²+2x-5=0 x1,2=1±√1+15/3=1±4/3
x1=1+4/3=5/3 x2=1-4/3=-1
b)2x²-5x-3=0
x1,2=5±√25+24/4=5±7/4
x1=5+7/4=3
x2=5-7/4=-1/2
3.
x1=-2 x2=-4 S=-6 P=8
x²+6x+8=0
