Question 463703
1. {{{sqrt(-36) = sqrt(36)*sqrt(-1) = 6i}}}

2.  {{{-sqrt(3)*sqrt(-3) = -sqrt(3)*sqrt(3)*sqrt(-1) = -3i}}}

3.  5i.  (similar to #1.)

4.  {{{sqrt(-25)*sqrt(-9) = sqrt(25)*sqrt(-1)*sqrt(9)*sqrt(-1)
=5i*3i = 15i^2 = -15}}}

5.  {{{(6i)^2 = 6^2*i^2 = -36}}}

6.  {{{(1/i)*((-i)/(-i))= (-i)/(-i^2) = (-i)/(-(-1)) = -i}}}