Question

已知{x+my}{x+ny]=x的2次方+2xy-8y的平方,求m的2次方n+m {n的2次方}的值

Answer 1

(x+my)(x+ny)
=x²+(m+n)y+mny²
=x²+2xy-8y²
所以mn=2
mn=-8
所以原式=mn(m+n)=-16

Answer 2

(x+my)(x+ny)
=x^2+(m+n)xy+mny^2
=x^2+2xy-8y^2
m+n=2 mn=-8
m^2n+mn^2
=mn(m+n)
=-8*2
=-16