1) _x²-3x-4_ =0 2)_ x²+2x-3_ =0
x+1 x-5
Умножаем крест накрест. x²+2x-3=0
x²-3x-4=0 D=4+12=16
D=9+16=25 x₁=(-2-4)/2= -6/2= -3.
x₁=(3+5)/2=8/2=4. x₂=(-2+4)/2=2/2=1.
x₂=(3-5)/2= -2/2= -1.
3) _x²+4x+3_ =0 4) _6x²+6x_ =0
x+2 x-1
x²+4x+3=0 6x²+6x=0
D=16-12=4 6x·(x+1)=0
x₁=(-4+2)/2= -2/2= -1. 6x=0 x+1=0
x₂=(-4-2)/2= -6/2= -3. x=0 x= -1.