Let n be a natural number. Show that if n is a perfect square, then 2n is not a perfect square.

Exercise 5: 10 points Let u be a natural number. Show that if n is a perfect square, then 2n is not a perfect square. (Reminder: a natural number a is a perfect square if there eau'sts a natural number k such that 71:162.) Extra Credit: 5 points Find all functions f : IR > R that satisfy: V017, y) E R2, f(m)f(y) + f(m + y) = my