Is the function $$f(x) = 7x + 11 \pmod{10}$$ invertible for all positive integers?
I don't know how to go about it, mainly because I have never dealt with functions such as this one.
Is the function $$f(x) = 7x + 11 \pmod{10}$$ invertible for all positive integers?
I don't know how to go about it, mainly because I have never dealt with functions such as this one.