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1.(a-2b)(a的2次方-3ab+b的2次方)2.(x的2次方+xy+y的2次方)(x的2次方-xy+y的2次方)

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(a-2b)(a的2次方-3ab+b的2次方)
=a³-3a²b+ab²-2a²b+6ab²-2b³
=a³-5a²b+7ab²-2b³
(x的2次方+xy+y的2次方)(x的2次方-xy+y的2次方)
=[(x²+y²)+xy][(x²+y²)-xy]
=(x²+y²)²-(xy)²
=x的4次方+2x²y²+y的4次方-x²y²
=x的4次方+x²y²+y的4次方