### Home > CCA2 > Chapter 6 > Lesson 6.2.4 > Problem6-142

6-142.

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, $9$ is the output. Write and solve the equation.

What do you do to both sides of the equation to 'undo' the square root?