2z²+9z-5=0
Δ=b²-4ac=9+40=49
x1,2=(-b=+/- √Δ)/2a
x1=(-3-7)/4=-10/4=-5/2
x2=(-3+7)/4=4/4=1
(2x+5)(x-1)=0
c)
radacinile opuse sunt
y1=5/2
y2=-1
pentru formarea ecuatiei
y²-Sy+p=0
S=y1+y2=5/2-1=3/2
P=y1.y2=5/2.(-1)=-5/2
ecuatia este
(y-3/2)(y+5/2)=0
4y²+4y-15=0