30 tháng 7 2015 lúc 12:45
x(x+4)(x+6)(x+10)+128
=x.(x+10)(x+4)(x+6)+128
=(x2+10x)(x2+10x+24)+128
=(x2+10x)[(x2+10x)+24]+128
=(x2+10x)2+24.(x2+10x)+128
=(x2+10x)2+8.(x2+10x)+16.(x2+10x)+128
=(x2+10x)(x2+10x+8)+16.(x2+10x+8)
=(x2+10x+8)(x2+10x+16)
=(x2+10x+8)(x2+2x+8x+16)
=(x2+10x+8)[x.(x+2)+8.(x+2)]
=(x2+10x+8)(x+2)(x+8)
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