x^3+3x^2-4=0 - chyba metodą grupowania wyrazów :)

[latex]x^3+3x^2-4=0 \\ \\x^3-x^2+4x^2-4=0\\ \\x^{2}(x-1)+4(x^{2}-1)=0\\ \\x^{2}(x-1)+4(x-1)(x+1)=0[/latex] [latex](x-1)(x^{2}+4(x+1))=0\\ \\(x-1)(x^{2}+4x+4)=0\\ \\(x-1)(x+2)^{2}=0\\ \\x-1=0\vee x+2=0\\ \\x=1\vee x=-2[/latex]