Numpy Error

hey take a look at this code in pycharm.`

import numpy as np
x = np.array( [ [1,3],[2,4] ] )
y = np.array([  [2,2],[3,5] ] )
print x*y
print x.dot(y)

So both dot() and array() are numpy function but . Why can't I just write

  x = array( [ [1,3],[2,4] ] )  
  y = array([  [2,2],[3,5] ] )

and get rid of "np".. moreover, when using dot() function , why don't pycharm accepts x.(np.dot(y)) ??