因式分解:(X2—1)(X+3)(X+5)+12

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因式分解:(X2—1)(X+3)(X+5)+12

因式分解:(X2—1)(X+3)(X+5)+12
因式分解:(X2—1)(X+3)(X+5)+12

因式分解:(X2—1)(X+3)(X+5)+12
(x^2-1)(x+3)(x+5)+12
=(x+1)(x-1)(x+3)(x+5)+12
=[(x-1)(x+5)][(x+3)(x+1)]+12
=(x^2+4x-5)(x^2+4x+3)+12
=[(x^2+4x-1)-4][(x^2+4x-1)+4]+12
=(x^2+4x-1)^2-16+12
=(x^2+4x-1)^2-4
=(x^2+4x-1+2)(x^2+4x-1-2)
=(x^2+4x+1)(x^2+4x-3).

可以换元