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 didn't see what he dropped in, but she did see what fell out: 9. What operations must she perform on 9 to undo what her machine did? Use this to find out what Caleb dropped in.
In this situation,
What do you do to both sides of the equation to 'undo' the square root?