Kirsta was working with the function machine shown at right, but when she turned her back, her little brother Caleb dropped in a number. She did not see what he dropped in, but she did see what fell out: $9$.

1. What operations must she perform on $9$ to undo what her machine did? Use this to determine what number Caleb dropped in.

   Hint (a):

   What number results in $9$ after adding $5$ and then taking the square root?

2. Write an equation for a machine that will undo Kirsta’s machine.

   Hint (b):

   How can you undo adding $5$ and then square rooting?