Question:
Find the product:
$(x-2 y+3)\left(x^{2}+4 y^{2}+2 x y-3 x+6 y+9\right)$
Solution:
$(\mathrm{x}-2 \mathrm{y}+3)\left(x^{2}+4 y^{2}+2 x y-3 x+6 y+9\right)$
$=(\mathrm{x}-2 \mathrm{y}+3)\left(x^{2}+4 y^{2}+9+2 x y+6 y-3 x\right)$
$=[x+(-2 y)+3]\left[x^{2}+(-2 y)^{2}+(3)^{2}-x \times(-2 y)-(-2 y) \times 3-3 \times x\right]$
$=(x)^{3}+(-2 y)^{3}+(3)^{3}-3(x)(-2 y)(3)$
$=x^{3}-8 y^{3}+27+18 x y$
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