a: \(x^3-4x=x\cdot x^2-x\cdot4\)
\(=x\left(x^2-4\right)\)
\(=x\left(x-2\right)\left(x+2\right)\)
b: \(xy-3x\)
\(=x\cdot y-x\cdot3\)
=x(y-3)
c: \(x^2+4xy+4y^2-25\)
\(=\left(x^2+4xy+4y^2\right)-25\)
\(=\left(x+2y\right)^2-5^2\)
\(=\left(x+2y+5\right)\left(x+2y-5\right)\)
d: \(x^2+25-10x\)
\(=x^2-2\cdot x\cdot5+5^2\)
\(=\left(x-5\right)^2\)
e: \(x^3-8y^3\)
\(=x^3-\left(2y\right)^3\)
\(=\left(x-2y\right)\left(x^2+2xy+4y^2\right)\)
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