Question

已知x>0,y>0,且x-4倍根号xy-5y=0.求代数式2x+根号xy+3x分之x+根号xy-y

的值

Answer 1

x-4倍根号xy-5y=0
(√x+√y)(√x-5√y)=0 x>0,y>0
√x-5√y=0
x=25y
2x+根号xy+3x分之x+根号xy-y
=(x+根号xy-y)/(2x+根号xy+3x)
=(25y+5y-y)/(50y+5y+75y)
=29/130