Exrpess each number in terms of i

Question

a. root-21
b. -root-59
c. -root-9
d. root-28

Answer 1

For a:
root(-21) = root( (21)*(-1) )
= root(21) * root(-1)
= root(21) * i

That should get you started

Answer 2

a.
sqrt(-21)
=sqrt(21*(-1))
=sqrt(21)*sqrt(-1)
=±sqrt(21) i

c.
-sqrt(-9)
=-sqrt(9*(-1))
=∓sqrt(9)*sqrt(-1)
=∓3i

Try problems a and d along the same lines. Post your results if you need confirmation.