Question

sendo z1= 2+3i, z2=-1+2i e z3= 1-i.  Determine z1.z2

Answer 1

$i^{2} = - 1$
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$z_{1}=2+3i$
$z_{2}=-1+2i$

$z_{1}*z_{2}=(2+3i)*(-1+2i)$
$z_{1}*z_{2}=2*(-1)+2*2i+3i*(-1)+3i*2i$
$z_{1}*z_{2}=-2+4i-3i+6i^{2}$
$z_{1}*z_{2}=-2+i+6(-1)$
$z_{1}*z_{2}=-2+i-6$
$z_{1}*z_{2}=-8+i$