Cho số phức <span class="MathJax_Preview" style="color: inherit; display: none;"></span><span id="MathJax-Element-1-Frame" class="mjx-chtml MathJax_CHTML" tabindex="0" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mstyle mathsize="1.44em"><mi>z</mi><mo>=</mo><mn>1</mn><mo>+</mo><mn>2</mn><mi>i</mi><mo>.</mo></mstyle></math>" role="presentation" style="font-size: 127%; position: relative;"><span id="MJXc-Node-1" class="mjx-math" aria-hidden="true"><span id="MJXc-Node-2" class="mjx-mrow"><span id="MJXc-Node-3" class="mjx-mstyle"><span id="MJXc-Node-4" class="mjx-mrow" style="font-size: 144%;"><span id="MJXc-Node-5" class="mjx-mi"><span class="mjx-char MJXc-TeX-math-I" style="padding-top: 0.199em; padding-bottom: 0.298em; padding-right: 0.003em;">z</span></span><span id="MJXc-Node-6" class="mjx-mo MJXc-space3"><span class="mjx-char MJXc-TeX-main-R" style="padding-top: 0.101em; padding-bottom: 0.298em;">=</span></span><span id="MJXc-Node-7" class="mjx-mn MJXc-space3"><span class="mjx-char MJXc-TeX-main-R" style="padding-top: 0.396em; padding-bottom: 0.347em;">1</span></span><span id="MJXc-Node-8" class="mjx-mo MJXc-space2"><span class="mjx-char MJXc-TeX-main-R" style="padding-top: 0.298em; padding-bottom: 0.445em;">+</span></span><span id="MJXc-Node-9" class="mjx-mn MJXc-space2"><span class="mjx-char MJXc-TeX-main-R" style="padding-top: 0.396em; padding-bottom: 0.347em;">2</span></span><span id="MJXc-Node-10" class="mjx-mi"><span class="mjx-char MJXc-TeX-math-I" style="padding-top: 0.445em; padding-bottom: 0.298em;">i</span></span><span id="MJXc-Node-11" class="mjx-mo"><span class="mjx-char MJXc-TeX-main-R" style="margin-top: -0.145em; padding-bottom: 0.347em;">.</span></span></span></span></span></span><span class="MJX_Assistive_MathML" role="presentation"><math xmlns="http://www.w3.org/1998/Math/MathML"><mstyle mathsize="1.44em"><mi>z</mi><mo>=</mo><mn>1</mn><mo>+</mo><mn>2</mn><mi>i</mi><mo>.</mo></mstyle></math></span></span><script type="math/tex" id="MathJax-Element-1">\Large z=1+2i.</script> Tìm môđun của số phức <span class="MathJax_Preview" style="color: inherit; display: none;"></span><span id="MathJax-Element-2-Frame" class="mjx-chtml MathJax_CHTML" tabindex="0" data-mathml="<math xmlns="http://www.w3.org/1998/Math/MathML"><mstyle mathsize="1.44em"><mrow class="MJX-TeXAtom-ORD"><mover><mi>z</mi><mo stretchy="false">¯</mo></mover></mrow><mo>.</mo></mstyle></math>" role="presentation" style="font-size: 127%; position: relative;"><span id="MJXc-Node-12" class="mjx-math" aria-hidden="true"><span id="MJXc-Node-13" class="mjx-mrow"><span id="MJXc-Node-14" class="mjx-mstyle"><span id="MJXc-Node-15" class="mjx-mrow" style="font-size: 144%;"><span id="MJXc-Node-16" class="mjx-texatom"><span id="MJXc-Node-17" class="mjx-mrow"><span id="MJXc-Node-18" class="mjx-munderover"><span class="mjx-stack"><span class="mjx-over" style="height: 0.096em; padding-bottom: 0.06em; padding-left: 0.067em;"><span id="MJXc-Node-20" class="mjx-mo" style="vertical-align: top;"><span class="mjx-char MJXc-TeX-main-R" style="padding-top: 0.298em; padding-bottom: 0.298em;">¯</span></span></span><span class="mjx-op"><span id="MJXc-Node-19" class="mjx-mi"><span class="mjx-char MJXc-TeX-math-I" style="padding-top: 0.199em; padding-bottom: 0.298em; padding-right: 0.003em;">z</span></span></span></span></span></span></span><span id="MJXc-Node-21" class="mjx-mo"><span class="mjx-char MJXc-TeX-main-R" style="margin-top: -0.145em; padding-bottom: 0.347em;">.</span></span></span></span></span></span><span class="MJX_Assistive_MathML" role="presentation"><math xmlns="http://www.w3.org/1998/Math/MathML"><mstyle mathsize="1.44em"><mrow class="MJX-TeXAtom-ORD"><mover><mi>z</mi><mo stretchy="false">¯</mo></mover></mrow><mo>.</mo></mstyle></math></span></span><script type="math/tex" id="MathJax-Element-2">\Large \bar{z}.</script> $

Cho số phức $\Large z=1+2i.$ Tìm môđun của số phức $\Large \bar{z}.$ $

4.9/5

Tác giả: Thầy Tùng

Đăng ngày: 18 Aug 2022

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Lời giải chi tiết

Câu hỏi:

Cho số phức $\Large z=1+2i.$ Tìm môđun của số phức $\Large \bar{z}.$

A.
$\Large \sqrt{5}.$
B.
-1.
C.
$\Large \sqrt{3}.$
D.
3.

Đáp án án đúng là: A

Lời giải chi tiết:

Chọn A

$\Large z=1+2i \Rightarrow \bar{z}=1-2i.$

Môđun của số phức $\Large \bar{z}$ là: $\Large |\bar{z}|=\sqrt{1^2+(-2)^2}=\sqrt{5}.$

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