Question

Tìm x, biết:

x²+6x+9 =0

Answer 1

x² + 6x + 9    = 0

x² + 2.3x +3² = 0

( x + 3 )²        = 0

=> x + 3         = 0

=>      x          = -3

Answer 2

\(x^2+6x+9=0\)

\(\Leftrightarrow\left(x+3\right)^2=0\)

\(\Leftrightarrow\)\(x+3=0\)

\(\Rightarrow\)\(x=0-3=-3\)

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