已知P=(x-y分之x^2)-(x-y分之y^2),Q=x-y+2y²/x+y当x>y>0时比较P,Q值的大小.

问题描述:

已知P=(x-y分之x^2)-(x-y分之y^2),Q=x-y+2y²/x+y当x>y>0时比较P,Q值的大小.

P=(x^2-y^2)/(x-y)=x+y=(x+y)^2/(x+y)=(x^2+y^2+2xy)/(x+y)
Q=(x^2+y^2)/(x+y),因此P>Q