a/ \(\left(x-3\right)^2+6\left(x-3\right)+9\)
\(=\left(x-3\right)^2+2.\left(x-3\right).3+3^2\)
\(=\left(x-3+3\right)^2=x^2\)
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b/ \(\left(x+2021\right)^2+2\left(x+2021\right)\left(x-2021\right)+\left(x-2021\right)^2\)
\(=\left(x+2021+x-2021\right)^2=4x^2\)
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c/ \(2022^2-2.2021.2022+2021^2\)
\(=\left(2022-2021\right)^2=1\)
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d/ \(\left(x+44\right)^2-88\left(x+44\right)+1936\)
\(=\left(x+44\right)^2-2.\left(x+44\right).44+44^2\)
\(=\left(x+44-44\right)^2=x^2\)
d: Ta có: \(\left(x+44\right)^2-88\left(x+44\right)+1936\)
\(=\left(x+44-44\right)^2\)
\(=x^2\)