Question

write (1+2i)(3+1)(2+i)-1in the form of a+in​

Answer 1

=(1+2i) 4 (2+i) -1

=4(2+i+4i+ 2 i^2 ) -1

= 4(2 +5i + 2×-1)-1 [ i^2 =-1]

= 4( 5i)-1

= 20 i -1

= -1 + 20 i