Chapter 1 - Foundations for Algebra - 1-6 Multiplying and Dividing Real Numbers - Practice and Problem-Solving Exercises - Page 42: 23

-30

$\sqrt 900$ means that we are supposed to find what number times itself equals 900. We recall that 30 times 30 is 900, so $\sqrt 900$ is 30. However, as we can see, there is a negative outside of the square root. This means that we multiply $\sqrt 900$, 30, by -1, giving us our final answer: -30.