if x=3i, y=2i and z=m+i, the expression xy^2z equals?

12i³m + 12i⁴

If      $${i}$$ =   $${\sqrt{-{\mathtt{1}}}}$$

then this simplifieds to 

12*-1im+12*-1*-1 = -12mi+12

if x=3i, y=2i and z=m+i, the expression xy^2z equals....so we have...

(3i)(2i)²(m + i) =

(3i)(4i²)(m+i) =

(12i³)(m + i) =

12i³m + 12i⁴