Răspuns :

x²-2x-3=0

x²-3x+x-3=0

x(x-3)+(x-3)=0

(x-3)(x+1)=0

1. x-3=0

x=3

2. x+1=0

x= -1

x∈{-1,3}

Targoviste44id

[tex]\it x^2-2x-3=0 \Rightarrow x^2+x-3x-3=0 \Rightarrow x(x+1)-3(x+1)=0 \Rightarrow\\\ \\\ \Rightarrow(x+1)(x-3)=0 \Rightarrow \begin{cases} \it x+1=0 \Rightarrow x_1=-1\\ \\ \it x-3=0 \Rightarrow x_2\ =\ 3\end{cases}[/tex]

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