Find the value of `sqrt(-16) xx sqrt(-25)`.

Answer

To find the value of \( \sqrt{-16} \times \sqrt{-25} \), we can follow these steps:

### Step 1: Rewrite the square roots
We can express the square roots of negative numbers using the imaginary unit \( i \), where \( i = \sqrt{-1} \). Therefore, we can rewrite the expression as:
\[ \sqrt{-16} = \sqrt{16} \times \sqrt{-1} = 4i \]
\[ \sqrt{-25} = \sqrt{25} \times \sqrt{-1} = 5i \]

### Step 2: Substitute the values into the expression
Now we can substitute these values back into the original expression:
\[ \sqrt{-16} \times \sqrt{-25} = (4i) \times (5i) \]

### Step 3: Multiply the terms
Now we can multiply the two terms:
\[ (4i) \times (5i) = 20i^2 \]

### Step 4: Simplify using the property of \( i \)
Recall that \( i^2 = -1 \). Therefore, we can simplify \( 20i^2 \):
\[ 20i^2 = 20 \times (-1) = -20 \]

### Final Answer
Thus, the value of \( \sqrt{-16} \times \sqrt{-25} \) is:
\[ \boxed{-20} \]

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