Question

已知（x-y-1)方+根号2 x+y+4=0,求x-3y的算术平方根

Answer 1

（x-y-1)方+根号2 x+y+4=0

x-y-1=0

x-y=1

2x+y+4=0

2x+y=-4

3x=-3

x=-1

y=-2

x-3y=-1+6=5

x-3y的算术平方根=根号5