The expression given in the image is:

$\sqrt{5} \times 3\sqrt{15}$

Step-by-step solution:

1. Multiply the constants:

   • There is an implicit constant of 1 in front of $\sqrt{5}$, so multiply $1 \times 3 = 3$.

2. Multiply the square roots: $\sqrt{5} \times \sqrt{15} = \sqrt{5 \times 15} = \sqrt{75}$

3. Now, simplify $\sqrt{75}$: $\sqrt{75} = \sqrt{25 \times 3} = \sqrt{25} \times \sqrt{3} = 5\sqrt{3}$

4. Finally, multiply by the constant 3: $3 \times 5\sqrt{3} = 15\sqrt{3}$

Final Answer:

$15\sqrt{3}$

Would you like further details or explanations?

Here are 5 related questions to further your understanding:

1. How do you simplify expressions with square roots?
2. Can you explain how to multiply two radical expressions with different radicands?
3. How do you handle square roots of numbers that aren't perfect squares?
4. What happens if you have cube roots instead of square roots?
5. How can you rationalize the denominator if there is a radical in the denominator?

Tip: When multiplying radicals, always try to simplify the numbers inside the square roots to their prime factorizations!