(x²+5x+2)(x²+5x+3)-12
= (x²+5x)²+5(x²+5x)+6-12
= (x²+5x)²+5(x²+5x)-6
= (x²+5x-1)(x²+5x+6)
= (x²+5x-1)(x+2)(x+3)
x²-32x+231
= (x-11)(x-21)
(x²+x+1)(x²+x+2) -12
= (x²+x)²+3(x²+x)+2-12
= (x²+x)²+3(x²+x)-10
= (x²+x-2)(x²+x+5)
= (x+2)(x-1)(x²+x+5)
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