1/ \(\left(3x-1\right)^2+2\left(3x-1\right)\left(2x+1\right)+\left(2x+1\right)^2\)
\(=\left(3x-1+2x+1\right)^2=\left(5x\right)^2=25x^2\)
2/ a. \(x^2-9+\left(x-3\right)^2\)
\(=\left(x-3\right)\left(x+3\right)+\left(x+3\right)^2\)
\(=\left(x+3\right)\left(x-3+x+3\right)\)
\(=2x\left(x+3\right)\)
b. \(x^3-3x^2+3x-1\)
\(=x^3-x^2+4x^2-4x+x-1\)
\(=\left(x^3-x^2\right)+\left(4x^2-4x\right)+\left(x-1\right)\)
\(=x^2\left(x-1\right)+4x\left(x-1\right)+\left(x-1\right)\)
\(=\left(x-1\right)\left(x^2+4x+1\right)\)
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