Question

Să se calculeze modulul nr complex z=√15-i.Dau coroană repede!​

Answer 1

 

$\displaystyle\bf\\z=\sqrt{15}-i\\\\Re~z=\sqrt{15}\\\\Im~z=-1\\\\Modul~(z)=|z|=\Big|\sqrt{15}-i\Big|=\\\\=\sqrt{\Big(Re~z\Big)^2+\Big(Im~z\Big)^2}=\\\\=\sqrt{\Big(\sqrt{15}\Big)^2+\Big(-1\Big)^2}=\\\\=\sqrt{15+1}=\sqrt{16}=4\\\\\boxed{\bf|z|=4}$