Tìm môđun của số phức <span class="MathJax_Preview" style="color: inherit;"><span class="MJXp-math" id="MJXp-Span-1"><span class="MJXp-mstyle" id="MJXp-Span-2"><span class="MJXp-mi MJXp-italic" id="MJXp-Span-3">z</span><span class="MJXp-mo" id="MJXp-Span-4" style="margin-left: 0.333em; margin-right: 0.333em;">=</span><span class="MJXp-mo" id="MJXp-Span-5" style="margin-left: 0em; margin-right: 0em;">(</span><span class="MJXp-mn" id="MJXp-Span-6">2</span><span class="MJXp-mo" id="MJXp-Span-7" style="margin-left: 0.267em; margin-right: 0.267em;">−</span><span class="MJXp-mi MJXp-italic" id="MJXp-Span-8">i</span><span class="MJXp-mo" id="MJXp-Span-9" style="margin-left: 0em; margin-right: 0em;">)</span><span class="MJXp-mo" id="MJXp-Span-10" style="margin-left: 0em; margin-right: 0em;">(</span><span class="MJXp-mn" id="MJXp-Span-11">1</span><span class="MJXp-mo" id="MJXp-Span-12" style="margin-left: 0.267em; margin-right: 0.267em;">−</span><span class="MJXp-mn" id="MJXp-Span-13">3</span><span class="MJXp-mi MJXp-italic" id="MJXp-Span-14">i</span><span class="MJXp-mo" id="MJXp-Span-15" style="margin-left: 0em; margin-right: 0em;">)</span></span></span></span><span id="MathJax-Element-1-Frame" class="mjx-chtml MathJax_CHTML MJXc-processing" tabindex="0"></span><script type="math/tex" id="MathJax-Element-1">\Large z=(2-i)(1-3i)</script> <span class="MathJax_Preview" style="color: inherit;"><span class="MJXp-math" id="MJXp-Span-16"><span class="MJXp-mstyle" id="MJXp-Span-17"><span class="MJXp-mrow" id="MJXp-Span-18"><span class="MJXp-mo" id="MJXp-Span-19" style="margin-left: 0.167em; margin-right: 0.167em;">|</span></span><span class="MJXp-mi MJXp-italic" id="MJXp-Span-20">z</span><span class="MJXp-mrow" id="MJXp-Span-21"><span class="MJXp-mo" id="MJXp-Span-22" style="margin-left: 0.167em; margin-right: 0.167em;">|</span></span><span class="MJXp-mo" id="MJXp-Span-23" style="margin-left: 0.333em; margin-right: 0.333em;">=</span><span class="MJXp-mn" id="MJXp-Span-24">2</span><span class="MJXp-msqrt" id="MJXp-Span-25"><span class="MJXp-surd"><span style="font-size: 134%; margin-top: 0.104em;">√</span></span><span class="MJXp-root"><span class="MJXp-rule" style="border-top: 0.08em solid;"></span><span class="MJXp-box"><span class="MJXp-mn" id="MJXp-Span-26">5</span></span></span></span></span></span></span><span id="MathJax-Element-2-Frame" class="mjx-chtml MathJax_CHTML MJXc-processing" tabindex="0"></span><script type="math/tex" id="MathJax-Element-2">\Large |z|=2\sqrt{5}</script>. $

Tìm môđun của số phức z=(2i)(13i) |z|=25. $

4.5/5

Tác giả: Thầy Tùng

Đăng ngày: 18 Aug 2022

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Câu hỏi:

Tìm môđun của số phức z=(2i)(13i)

Đáp án án đúng là: D

Lời giải chi tiết:

Chọn D
Ta có z=(2i)(13i)=17i

Môđun của số phức z là: |z|=|17i|=52.