a) -2x²+x+3=0
x=-1+-√1²-4*(-2)*3/2*(-2)
x=-1+-√1+24/-4
x=-1+-√25/-4
x=-1+-5/-4
x=- -1+-5/4
unde x₁=- -1+5/4
x₂= - -1-5/4
deci x₁=-1 iar x₂=3/2
b) 2x²-4x+2=0
x²-2x+1=0
(x-1)²=0
x-1=0
x=1
c) 3x²+x+1=0
x=-1+-√1²-4*3*1/2*3
x=-1√+-√1-12/6
x=-1+-√-11/6
x ∉ R
d) x²-4=0
x²=4
x+-2
x₁=2 si x₂=-2
e) 2x²+3x=0
x*(2x+3)=0
x=0 si 2x+3=0
x₁=0 si x₂=-3/2
