已知(x+my)(x+ny)=x2+2xy-8y2,求m2n+mn2的值.

已知(x+my)(x+ny)=x2+2xy-8y2,求m2n+mn2的值.


∵(x+my)(x+ny)=x2+2xy-8y2,∴x2+nxy+mxy+mny2=x2+(m+n)xy+mny2=x2+2xy-8y2,∴m+n=2,mn=-8,∴m2n+mn2=mn(m+n)=-8×2=-16.



已知(x+my)(x+ny)=x2+2xy-8y2,求m2n+mn2的值.


∵(x+my)(x+ny)=x2+2xy-8y2,∴x2+nxy+mxy+mny2=x2+(m+n)xy+mny2=x2+2xy-8y2,∴m+n=2,mn=-8,∴m2n+mn2=mn(m+n)=-8×2=-16.



已知(x+my)(x+ny)=x的+2xy - 8y,求(m+n)mn的值.快啊,


(x+my)(x+ny)
=x^2+(m+n)xy+mny^2
=x^2+2xy-8y^2
對應項係數相等
m+n=2,mn=-8
mn(m+n)=-8×2=-16