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Câu hỏi: Cho số phức $z$ thỏa mãn $(2-i)z-2=2+3i$. Modun của z bằng:
A. $\left| z \right|=5$.
B. $\left| z \right|=\dfrac{5\sqrt{3}}{3}$.
C. $\left| z \right|=\dfrac{5\sqrt{5}}{3}$.
D. $\left| z \right|=\sqrt{5}$.
Ta có: $\left( 2-i \right)z-2=2+3i\Leftrightarrow \left( 2-i \right)z=4+3i\Leftrightarrow z=\dfrac{4+3i}{2-i}=1+2i\Rightarrow \left| z \right|=\sqrt{5}$.
A. $\left| z \right|=5$.
B. $\left| z \right|=\dfrac{5\sqrt{3}}{3}$.
C. $\left| z \right|=\dfrac{5\sqrt{5}}{3}$.
D. $\left| z \right|=\sqrt{5}$.
Ta có: $\left( 2-i \right)z-2=2+3i\Leftrightarrow \left( 2-i \right)z=4+3i\Leftrightarrow z=\dfrac{4+3i}{2-i}=1+2i\Rightarrow \left| z \right|=\sqrt{5}$.
Đáp án D.