Question

用十字相乘法分解因式x^2-(p^2+q^2)x+pq(p+q)(p-q)=0

Answer 1

pq(p^2-q^2)=pq(p-q)(p+q)=(p^2-pq)(pq+q^2)

x^2-(p^2+q^2)x+(p^2-pq)(pq+q^2)=0

[x-(p^2-pq)][x-(pq+q^2)=0