①根号3-a有意义的条件为a≤3
②根号a(a-2)+1(a>2)
=√(a²-2a+1)
=√(a-1)²
=a-1
③因为(x-1)平方+|y+2|+根号z-3=0
所以x-1=0,
y+2=0,
z-3=0.
解得x=1,
y=-2,
z=3
所以 x+y+z=1-2+3=2
①根号3-a有意义的条件为a≤3
②根号a(a-2)+1(a>2)
=√(a²-2a+1)
=√(a-1)²
=a-1
③因为(x-1)平方+|y+2|+根号z-3=0
所以x-1=0,
y+2=0,
z-3=0.
解得x=1,
y=-2,
z=3
所以 x+y+z=1-2+3=2