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5a+5b-ax-bx=5(a+b)-x(a+b)=(a+b)(5-x)
m^2-mn-2n+2m=m(m-n)+2(m-n)=(m-n)(m+2)
10by-25bx-6ay+15ax=2y(5b-3a)-5x(5b-3a)=(5b-3a)(2y-5x)
m^4+2-m-2m^3=m(m^3-1)-2(m^3-1)=(m^3-1)(m-2)
y-y^2-y^3+y^4y=y((1-y)-y^2(1-y))=y(1-y)()1-y^2)
x^2y-z^2x+y^2x-yz^2 =xy(x+y)-z ^2(x+y)=(x+y)(xy-z ^2)
x^4-3x^3+3x^2-9x= x^3(x-3)+3x(x-3)=(x-3)(x^3+3x)=x(x-3)(x^2+3)
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