X²(x+4)-20x(x+4)+100(x+4)=(x+4)(x²-20x+100)=(x+4)(x-10)²
a²-36-2a(36-a²)-a²(36-a²)=-(36-a²)-2a(36-a²)-a²(36-a²)=(36-a²)(-1-2a-a²)=-(6-a)(6+a)(1+2a+a²)=(a-6)(6+a)(1+a)²
(m-n)(n³-p³)-(n-p)(m³-n³)=(m-n)(n-p)(n²+np+p²)-(n-p)(m-n)(m²+mn+n²)=(m-n)(n-p)(n²+np+p²-m²-mn-n²)=(m-n)(n-p)(np+p²-m²-mn)=(m-n)(n-p)(p-m)(p+m+n)