Verified answer

1) √15b × √3b

Square each side to get rid of the square root. Hence, 15b x 3b

Multiply the equation. 45b^2

2) √5(2√10+√2x)

Square the entire equation. So, √5^2 x (2√10+√2x)^2

When you square a square root, the square root goes away. So, 5 x (2√10+√2x)(2√10+√2x)

Use the distribution property to simplify the parenthesis.

So, 5 x (4√10 + 2√20x + 2√20x + 2x)

Simplify further. So, 5 x (4√10 + 4√20x + 2x)

Use the distribution property to simplify further.

So, 20√10 + 20√20x + 10x

To simplify further, square the entire equation.

So, (20√10 + 20√20x + 10x)^2

(400x10 + 400x20x + 100x^2)

(4000 + 8000x + 100x^2)

or, (100x^2 + 8000x + 4000)

I am not sure of this one.