Question

Evaluate the following.
Click on "Not a real number" if applicable.

Answer 1

Answer:

1) $\sqrt{-64}$ is not a real number.

2) $-\sqrt{25} =-5$

Step-by-step explanation:

1) The square root of a number is defined for real numbers if and only if the number under the square root sign is greater than or equal to zero.

This implies that $\sqrt{-64}$ is not a real number because $-64\:<\:0$

2) $-\sqrt{25} =-\sqrt{5^2} =-5$.

The number under the square root sign is $25$, which is greater than zero. Note that the negative sign is not inside the square root sign, it is outside it.