Question 75897
{{{ sqrt(-6) * sqrt(-15) }}}
{{{ (i)sqrt(6) * (i)sqrt(15) }}}
now ...  i * i = i^2 = -1
{{{ -1sqrt(6*15) }}}
Factor out 6 and 15
6 = 3 * 2
15 = 3 * 5
6 * 15 = 2 * 3 * 3 * 5
{{{ -1sqrt(2*3*3*5) }}}
Take out the pairs
{{{ -1(3)sqrt(2*5) }}}
Multiply
{{{ -3sqrt(10) }}}