1)(x-5)(x+3)=(1-3x)(x+3)
xˇ2 -2x -15 = x+3 -3xˇ2-9x
4xˇ2+6x-18=0
2xˇ2 +3x -9=0
x1=3/2, x2=-3 ( D = 9+72=81, odm. iz 81 = 9, x1=1/4.(-3+9)=6/4=3/2, x2=1/4.(-3-9)=1/4.(-12)=-3
2)xˇ4-2xˇ2=8, xˇ4-2.xˇ2 - 8=0
xˇ2 = z, zˇ2-2z-8=0, z1=4,z2=-2
xˇ2=z1=4, /x/=2, x1=2,x2= -2
xˇ2 = -2 nevozmožno,