How did you get that? You need to be careful when you are using symbols ^ and x
Can you express 1 as a power of 11? (Note: by power here we mean repeated application of group operation so 11^5 = 5). Say it is 'n'
Once you know that ф(1)= ф(11^n) = ф(11)^n
Once we know ф(1), ф(x) should be easy, right?