Question

Giúp mk câu 21

Answer 1

Câu 21: \(z^2+2z+11=0\)

=>\(z^2+2z+1=-10\)

=>\(\left(z+1\right)^2=-10\)

=>\(z=-1\pm i\cdot\sqrt{10}\)

=>\(\left|z_1\right|=\left|z_2\right|=\sqrt{\left(-1\right)^2+10}=\sqrt{11}\)

\(A=\left(\left|z_1\right|\right)^2+\left(\left|z_2\right|\right)^2=11+11=22\)
=>Chọn B