Question

Sejam os números complexos z1=1+3i,  z2=5-4i,  z3=-2i, Calcule:

a) Z1+z2+z3

b)z1.z2.z3

Answer 1

a) Z1+z2+z3

$1+3i+5-4i-2i = \boxed{6-3i}$

b) z1.z2.z3


$(1+3i)\cdot(5-4i)\cdot(-2i) = \\\\ (1+3i)\cdot(5-4i) = 5-4i+15i-12i^2\\\\ \boxed{i^2=-1}\\\\ \boxed{(17+11i)}$

$(7+11i)\cdot(-2i) = -14i-22i^2\\\\ \boxed{-14i+22}$