已知x,y满足√（x+3y-1）+| 2x-y-9 |=0求5/4x+4的平方根.
问题描述：
已知x,y满足√（x+3y-1）+| 2x-y-9 |=0求5/4x+4的平方根.
答
√（x+3y-1）+| 2x-y-9 |=0
∴﹛x+3y-1=0
2x-y-9=0
解得x=4,y=-1
5/4x+4
=5+4
=9
∴5/4x+4的平方根=±√9=±3