Question

x2+2xy-8Y2=(x+my)(x+ny)

Answer 1

已知(x+my)(x+ny)=x^2+2xy-8y^2

求(m+n)*mn的值

m,n是系数,(x+my)(x+ny)=x^2+(m+n)y+mny^2=x^2+2xy-8y^2

等式两边系数相等,有

m+n=2

mn=-8

m=4 n=-2 或m=-2 n=4