Question

若m÷(x-2)+n÷(x+1)=(x-8)÷(x-2)(x+1),则mn=?

Answer 1

m/(x-2)+n/(x+1)=(x-8)/[(x+1)(x-2)]

m(x+1)+n(x-2)=(x-8)

mx+m+nx-2n=x-8

(m+n)x+(m-2n)=x-8

m+n=1

m-2n=-8

解方程组：

m=-2,n=3

mn=-6