Verified answer

5√39 x √26 =

5√(39 x 26) =

5√(3 x 13 x 2 x 13) =

5 x 13 x √(3 x 2) =

65√6

Edit:

5√(3 x 13 x 2 x 13) = 5√(13^2 x 2 x 3) OK?

Now we can write it as 5 x 13√(2 x 3).

Then multiply 5 by 13 out of radical sign and 2 by 3 under it :

= 65√6

The most important thing to remember is sqrt(a * b) = sqrt(a) * sqrt(b), and that sqrt(a^2) = a

5 * sqrt(39) * sqrt(26) =>

5 * sqrt(3) * sqrt(13) * sqrt(2) * sqrt(13) =>

5 * 13 * sqrt(3 * 2) =>

65 * sqrt(6)

EDIT:

Where did the 3 and 2 come from? Do you know how to multiply? I gave you the rules. You are going to have to make some conceptual leaps from time to time, because that's what learning involves. If you need everything spelled out for you in a step by step process, then you're going to have a horrible existence.

39 = 13 * 3

26 = 13 * 2

Was that so hard?

5 sq rt 39 * sq rt 26= 5 sq rt 1014 5 sq rt 169* sq rt 6= 65 sqrt 6