Question

Express each of the complex number given in the Exercises $1$ to $10$ in the form $a+ib$.
$i^9+i^{19}$

Answer 1

$i=\sqrt{-1}\Rightarrow i^2=-1$

$i^9+i^{19}$

$=i\times i^8+i\times i^{18}$

$=i\times (-1{)}^4+i\times (-1{)}^9$

$=i\times 1+i\times (-1)$

$=0+i\times 0$