Show that when the square of an odd integer is divided by 4, the remainder is always
Let f(x) = x^2− 2x. Find all real numbers x such that f(x) = f(f(x)).
\(f(x) = f(f(x))\)
\(x^2 - 2x = (x^2-2x)^2 - 2(x^2-2x)\)
Let \(x^2 - 2x = y.\)
\(y = y^2 - 2y\)
\(0 = y^2 - 3y\)
\(y = 0, 3\)
Now plug x back in.
\(x^2 - 2x = 0\)
\(\boxed{x = 0, 2}\)
\(x^2 - 2x = 3\)
\(\boxed{x = 3, -1}\)