Giải:
\(\left(x+2\right)^2+\left(x-3\right)^2-2\left(x-1\right)\left(x+1\right)=9\)
\(\Leftrightarrow x^2+4x+4+x^2-6x+9-2\left(x^2-1\right)=9\)
\(\Leftrightarrow x^2+4x+4+x^2-6x+9-2x^2+2=9\)
\(\Leftrightarrow4x+4-6x+9+2=9\)
\(\Leftrightarrow-2x+15=9\)
\(\Leftrightarrow-2x=-6\)
\(\Leftrightarrow x=3\)
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\(\left(x+2\right)^2+\left(x^2-3\right)^2-2\left(x-1\right)\left(x+1\right)=9\)
\(\left(x^2+4x+4\right)+\left(x^2-6x+9\right)-2\left(x^2-1\right)=9\)
\(x^2+4x+4+x^2-6x+9-2x^2+2=9\)
\(-2x+15=9\)
\(-2x=-6\)
x=3
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