Răspuns :
[tex]\it i\cdot i=-1\\ \\ a)\ \ (1+i)(1+2i)-3(2-i)=1+2i+i-2-6+3i=-7+6i\\ \\ b)\ \ (2+i)(3-2i)-(1-i)=6-4i+3i+2-1+i=7[/tex]
[tex]\it i\cdot i=-1\\ \\ a)\ \ (1+i)(1+2i)-3(2-i)=1+2i+i-2-6+3i=-7+6i\\ \\ b)\ \ (2+i)(3-2i)-(1-i)=6-4i+3i+2-1+i=7[/tex]