ANSWER
[tex]5 \sqrt{10} [/tex]
EXPLANATION
We want to simplify:
[tex]5 \sqrt{10} [/tex]
We need to check for any perfect square under the radical sign.
But unfortunately, 10 is the product of two prime numbers.
That is
[tex]10 = 5 \times 2[/tex]
Since there is no perfect square under the radical sign, it means
[tex]5 \sqrt{10} [/tex]
is already in its simplest form.
Hence the correct answer is
[tex]5 \sqrt{10} [/tex]
