海贼王特别篇有多少:初一数学题,(急需答案)

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因式分解:(1-m^)(1-n^)-4mn
注:^是平方

(1-m^)(1-n^)-4mn
=1-m^-n^+m^n^-4mn
=1-m^-n^+m^n^-2mn-2mn
=m^n^-2mn+1-(m^+n^+2mn)
=(mn-1)^-(m+n)^
=(mn+m+n-1)(mn-m-n-1)

(mn-1+m+n)(mn-1-m-n)

(1-m^2)(1-n^2)-4mn
=(nm-m-n-1)(nm+m+n-1)

(1-m^)(1-n^)-4mn
=1-m^2-n^2+m^2n^2-4mn
=(1-2mn+m^2n^2)-(m^2+n^2+2mn)
=(1-mn)^2-(m+n)^2
=(1-m-n-mn)(1+m+n-mn)