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$\begin{aligned}&3a^2 - 2a + 1 - a^2+5a - 6\\=&(3a^2 - a^2)+(-2a + 5a)+(1 - 6)\\=&2a^2 + 3a - 5\end{aligned}$
$\begin{aligned}&(4x - 3y)-[-(3y - x)+(x - y)]\\=&4x - 3y-(-3y + x + x - y)\\=&4x - 3y-(-4y + 2x)\\=&4x - 3y + 4y - 2x\\=&2x + y\end{aligned}$
$\begin{aligned}&(-x^3\cdot x^5)^2\div(-x^2)^3\\=&(-x^{3 + 5})^2\div(-x^{2\times3})\\=&(-x^8)^2\div(-x^6)\\=&x^{16}\div(-x^6)\\=&-x^{16 - 6}\\=&-x^{10}\end{aligned}$
$解:原式=(a2+9)2-(9-a2)(a2-9)$
$=(a2+9)2+(a2-9)2$
$=a^{4}+18a2+81+a^{4}-18a+81$
$=2a^{4}+162$
解:原式= $(a + 7)(a - 7)$
解:原式=$(a - 2b)^2$
$\begin{aligned}&m^2(m - 2)+4(2 - m)\\=&m^2(m - 2)-4(m - 2)\\=&(m - 2)(m^2 - 4)\\=&(m - 2)(m + 2)(m - 2)\\=&(m - 2)^2(m + 2)\end{aligned}$
$\begin{aligned}&(y + 2x)^2-(x + 2y)^2\\=&[(y + 2x)+(x + 2y)][(y + 2x)-(x + 2y)]\\=&(y + 2x + x + 2y)(y + 2x - x - 2y)\\=&(3x + 3y)(x - y)\\=&3(x + y)(x - y)\end{aligned}$