Question

x平方-2xy-3y平方=0可变为(x+y)(x-3y)=0则xy+4y平方分之xy-2y平方的值

Answer 1

(x+y)(x-3y)=0

x=-y或x=3y

当x=-y时

(xy-2y²)/(xy+4y²)=(-y²-2y²)/(-y²+4y²)=-1

当x=3y时

(xy-2y²)/(xy+4y²)=(3y²-2y²)/(3y²+4y²)=1/7