Răspuns :
(2x+1)²-(3x-1)(2x+1)+(x-2)²=
4x²+4x+1-(6x²+3x-2x-1)+x²-4x+4=
4x²+4x+1-6x²-x+1+x²-4x+4=
-x²-x+6=0 inmultim -1
x²+x-6=0
Δ=1+24=25
x₁=(-1+5)/2=4/2=2
x₂=(-1-5)/2=-6/2=-3
4x²+4x+1-(6x²+3x-2x-1)+x²-4x+4=
4x²+4x+1-6x²-x+1+x²-4x+4=
-x²-x+6=0 inmultim -1
x²+x-6=0
Δ=1+24=25
x₁=(-1+5)/2=4/2=2
x₂=(-1-5)/2=-6/2=-3