Its not true. No matter how many 9s you make the first X equal to, when you multiply it by 10, there would be a 0 in the last spot when you subtract the second .9repeating. so essentially it would be
x=.9repeating to infinity
10x=9.9repeating to infinity-1 with a 0 at the end
9x=8.9repeating to infinity - 1 with a 1 at the end
x=.9repeating to infinity.