Question

Efetue a seguinte operação(1+2i)×(2+i)

Answer 1

$(1+2i).(2+i)= \\ 2+i+4i+2i^2= \\ 2i^2+5i+2=0 \\ \\ delta=25-16 \\ delta=9 \\ \\ i'= \frac{-5+ \sqrt{9}}{2.2} = \frac{-5+3}{4}=- \frac{2}{4} =- \frac{1}{2} \\ \\ i''= \frac{-5- \sqrt{9}}{2.2} = \frac{-5-3}{4}=- \frac{8}{4}=-2$

Answer 2

2 + i + 4i + 2i²
2 + 5i + 2i²