why lim((x^2-x+1)^(1/2)+x,x=-oo,dir='below') is red error

edit

x=-oo, negative infinity,the answei is appear,but red error,1/2 is right?

lim((x^2-x+1)^(1/2)+x,x=-oo,dir='below')

Error in lines 0-2
Traceback (most recent call last):
  File "/projects/9e8c4ed8-0b57-4535-b8f1-a0d0ef1b015b/.sagemathcloud/sage_server.py", line 841, in execute
    exec compile(block+'\n', '', 'single') in namespace, locals
  File "<string>", line 1
    )
    ^
SyntaxError: invalid syntax