[Toán 6]

I

i_am_challenger

[TEX]X^2 +3x + 2 = 0[/TEX]
[TEX]\Leftrightarrow x^2 + 2x +x +2 = 0[/TEX]
[TEX]\Leftrightarrow x(x+2) + (x+2)=0[/TEX]
[TEX]\Leftrightarrow (x+2)(x+1) = 0[/TEX]
[TEX]\Leftrightarrow \left[\begin{x+1=0}\\{x+2=0}[/TEX]
[TEX]\Leftrightarrow \left[\begin{x= -1}\\{x=-2}[/TEX]
 
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