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第7页

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 $\begin{aligned}&2b\cdot(3ab)^2\\=&2b\cdot9a^2b^2\\=&18a^2b^3\end{aligned}$

 $\begin{aligned}&(a + 2b)(2b - a)+(a - b)^2\\=&(2b + a)(2b - a)+(a - b)^2\\=&(2b)^2 - a^2+a^2 - 2ab + b^2\\=&4b^2 - a^2+a^2 - 2ab + b^2\\=&5b^2-2ab\end{aligned}$

 $\begin{aligned}&2a^3 - 8a\\=&2a(a^2 - 4)\\=&2a(a + 2)(a - 2)\end{aligned}$

 $\begin{aligned}&3ax^2 - 6axy + 3ay^2\\=&3a(x^2 - 2xy + y^2)\\=&3a(x - y)^2\end{aligned}$

 $\begin{aligned}&2b^2(b - 1)-2(b - 1)\\=&2(b - 1)(b^2 - 1)\\=&2(b - 1)(b + 1)(b - 1)\\=&2(b - 1)^2(b + 1)\end{aligned}$