1)x²(x+4)-20x(x+4)+100(x+4)=(x+4)(x²-20x+100)=(x+4)(x-10)²
2)a²-36-2a(36-a²)-a²(36-a²)=(36-a²)(-1-2a-a²)=(a²-36)(a²+2a+1)=(a²-36)(a+1)²
3)a²(b-1)-b²(a-1)=a²b-a²-b²a+b²=ab(a-b)+(b²-a²)=-ab(b-a)+(b-a)(b+a)=(b-a)(-ab+b+a)
4)(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)(n(p-m)+(p-m)(p+m))=(m-n)(n-p)(p-m)(n+p+m)