## Differential Equations and Linear Algebra (4th Edition)

$\frac{1-13i}{10}$
We know that $i^2=-1$ $z_1z_2=(4-i)(1+3i)=4+12i-i+3=7+11i$ $z_1/z_2=\frac{4-i}{1+3i}=\frac{(4-i)(1-3i)}{(1+3i)(1-3i)}=\frac{4-12i-i-3}{1+9}=\frac{1-13i}{10}$