假设存在,设(x^2+2x+5)(x^2+ax+b)=x^4+px^2+q
展开(x^2+2x+5)(x^2+ax+b)=x^4+(a+2)x^3+(2a+b+5)x^2+(5a+2b)x+5b
对比系数,有
a+2=0,5a+2b=0,p=2a+b+5,q=5b
a=-2,b=5
p=6,q=25
假设存在,设(x^2+2x+5)(x^2+ax+b)=x^4+px^2+q
展开(x^2+2x+5)(x^2+ax+b)=x^4+(a+2)x^3+(2a+b+5)x^2+(5a+2b)x+5b
对比系数,有
a+2=0,5a+2b=0,p=2a+b+5,q=5b
a=-2,b=5
p=6,q=25