1)4х^2-4x-1=0
D=16-4*-4*(-1)=16-16=0
Net kornei
2)3x^2-4=0
3x^2=4
x^2=0,75
3)9x^2+8=18x
9x^2-18x+8=0
D=324-4*9*8=324-288=36=6^2
x^1=18-6/18=0,6
x^2=18+6/18=1,3
4)2x=-x^2-1
x^2+2x+1=0
D=-4-4*1*1=0
Net kornei
5)20x+25x^2=-4
25x^2+20x+4=0
D=400-4*25*4=400-400=0
Net kornei
6)-1-4x^2=0
-4x^2=1
x^2=-0,25
7)0,3-x^2=0
-x^2=-0,3
x=3
8)12-17x-5x^2=0
5x^2+17x-12=0
D=289-4*5*(-12)=-289+240=49=7^2
x^1=-17-7/10=-2,4
x^2=-17+7/10=-1