Question

X二次方=3XY-4Y方=0（Y≠0）求X+Y分之X-Y

Answer 1

X²+3XY-4Y²=0

(X+4Y)(X-Y)=0

X=-4Y,X=Y

若X=-4Y,(X-Y)/(X+Y)=(-4Y-Y)/(-4Y+Y)=-5Y/(-3Y)=5/3

若X=Y,(X-Y)/(X+Y)=(Y-Y)/(Y+Y)=0