1/x +4/y=2
1/2(1/x+4/y)=1
所以x+y=1/2(1/x+4/y)(x+y)
=1/2(1+y/x+4x/y+4)
=1/2(5+y/x+4x/y)=5/2+1/2(y/x+4x/y)>=5/2+1/2(2根号4)=5/2+2=9/2
所以MIN=9/2x和y的值？当且仅当y/x=4x/y时不等式成立此时4x^2=y^22x=y又1/x+4/y=2y+4x=2xy2x+4x=4x^26x=4x^26=4xx=3/2所以y=3