a) Ta có: \(8x^3y^4+2xy^2-8x^2y^3\)
\(=2xy^2\left(4x^2y^2+1-4xy\right)\)
\(=2xy^2\left[\left(2xy\right)^2-2\cdot2xy\cdot1+1\right]\)
\(=2xy^2\cdot\left(2xy-1\right)^2\)
b) Ta có: \(x^3-27-\left(x-3\right)\left(3x+13\right)\)
\(=\left(x-3\right)\left(x^2+3x+9\right)-\left(x-3\right)\left(3x+13\right)\)
\(=\left(x-3\right)\left(x^2+3x+9-3x-13\right)\)
\(=\left(x-3\right)\left(x^2-4\right)\)
\(=\left(x-3\right)\left(x-2\right)\left(x+2\right)\)
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