若(x+y-5)²+根号下x-y+1=0,求-4x+3y的算术平方根

题目

若(x+y-5)²+根号下x-y+1=0,求-4x+3y的算术平方根

答案

∵(x+y-5)²+√（x-y+1）=0
∴x+y-5=0,x-y+1=0得x=2,y=3
故√（-4x+3y）=√1=1