Question

（m+n)^3+2mn(1-m-n)-1

Answer 1

（m+n)^3+2mn(1-m-n)-1

=(m+n)^3-1-2mn(m+n-1)

=(m+n-1)(m^2+mn+n^2)-2mn(m+n-1)

=(m+n-1)(m^2+n^2-mn)

(a^2+a+1)(a^2+a+2)-12

=(a^2+a)^2+3(a^2+a)+2-12

=(a^2+a+5)(a^2+a-2)

=(a^2+a+5)(a+2)(a-1)

12x^4-56x^3+89x^2-56x+12

=(x-2)(12x^3-32x^2+25x-6)

=(x-2)(2x-1)(6x^2-13x+6)

=(x-2)(2x-1)(2x-3)(3x-2)