已知X/Y=2,则X²+2XY-3Y²/X²-XY+Y²=?

问题描述:

已知X/Y=2,则X²+2XY-3Y²/X²-XY+Y²=?

X/Y=2,X=2Y
(X²+2XY-3Y²)/(X²-XY+Y²)=(4Y²+2*2Y*Y-3Y²)/(4Y²-2Y*Y+Y²)=5Y²/3Y²=5/3