1. ## Simplify the following

a) √3 x √15
b) √32 x √24
c) 2√5 x 5√2

2. Remember that $\sqrt{ab}=\sqrt{a}\times\sqrt{b}$

And that $\sqrt{x}\times\sqrt{x}=x$

1) $\sqrt{15}=\sqrt{3}\times\sqrt{5}$

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

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

How would this simplify?

2) $\sqrt{32}$

$=\sqrt{16}\times\sqrt{2}$

$=4\times\sqrt{2}$

And

$\sqrt{24}$

$=\sqrt{4}\times\sqrt{6}$

$=2\times\sqrt{6}$

Substitute these into the equation and then simplification should become clear.

3)Write this as:

$2\times5\times\sqrt{2}\times\sqrt{5}$

Simplifying from here should be straightforward.

Reply if you are still stuck and I'll try to be of more assistance.