Cho hai 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-mrow" id="MJXp-Span-3"><span class="MJXp-msubsup" id="MJXp-Span-4"><span class="MJXp-mrow" id="MJXp-Span-5" style="margin-right: 0.05em;"><span class="MJXp-mi MJXp-italic" id="MJXp-Span-6">z</span></span><span class="MJXp-mrow MJXp-script" id="MJXp-Span-7" style="vertical-align: -0.4em;"><span class="MJXp-mn" id="MJXp-Span-8">1</span></span></span></span><span class="MJXp-mo" id="MJXp-Span-9" style="margin-left: 0.333em; margin-right: 0.333em;">=</span><span class="MJXp-mn" id="MJXp-Span-10">4</span><span class="MJXp-mo" id="MJXp-Span-11" style="margin-left: 0.267em; margin-right: 0.267em;">−</span><span class="MJXp-mn" id="MJXp-Span-12">3</span><span class="MJXp-mi MJXp-italic" id="MJXp-Span-13">i</span></span></span></span><span id="MathJax-Element-1-Frame" class="mjx-chtml MathJax_CHTML MJXc-processed" tabindex="0" style="font-size: 127%;"><span id="MJXc-Node-1" class="mjx-math"><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-texatom"><span id="MJXc-Node-6" class="mjx-mrow"><span id="MJXc-Node-7" class="mjx-msubsup"><span class="mjx-base" style="margin-right: -0.003em;"><span id="MJXc-Node-8" class="mjx-texatom"><span id="MJXc-Node-9" class="mjx-mrow"><span id="MJXc-Node-10" 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 class="mjx-sub" style="font-size: 70.7%; vertical-align: -0.212em; padding-right: 0.071em;"><span id="MJXc-Node-11" class="mjx-texatom" style=""><span id="MJXc-Node-12" class="mjx-mrow"><span id="MJXc-Node-13" class="mjx-mn"><span class="mjx-char MJXc-TeX-main-R" style="padding-top: 0.396em; padding-bottom: 0.347em;">1</span></span></span></span></span></span></span></span><span id="MJXc-Node-14" 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-15" class="mjx-mn MJXc-space3"><span class="mjx-char MJXc-TeX-main-R" style="padding-top: 0.396em; padding-bottom: 0.347em;">4</span></span><span id="MJXc-Node-16" 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-17" class="mjx-mn MJXc-space2"><span class="mjx-char MJXc-TeX-main-R" style="padding-top: 0.396em; padding-bottom: 0.347em;">3</span></span><span id="MJXc-Node-18" class="mjx-mi"><span class="mjx-char MJXc-TeX-math-I" style="padding-top: 0.445em; padding-bottom: 0.298em;">i</span></span></span></span></span></span></span><script type="math/tex" id="MathJax-Element-1">\Large {{z}_{1}}=4-3i</script> và <span class="MathJax_Preview" style="color: inherit;"><span class="MJXp-math" id="MJXp-Span-14"><span class="MJXp-mstyle" id="MJXp-Span-15"><span class="MJXp-mrow" id="MJXp-Span-16"><span class="MJXp-msubsup" id="MJXp-Span-17"><span class="MJXp-mrow" id="MJXp-Span-18" style="margin-right: 0.05em;"><span class="MJXp-mi MJXp-italic" id="MJXp-Span-19">z</span></span><span class="MJXp-mrow MJXp-script" id="MJXp-Span-20" style="vertical-align: -0.4em;"><span class="MJXp-mn" id="MJXp-Span-21">2</span></span></span></span><span class="MJXp-mo" id="MJXp-Span-22" style="margin-left: 0.333em; margin-right: 0.333em;">=</span><span class="MJXp-mn" id="MJXp-Span-23">7</span><span class="MJXp-mo" id="MJXp-Span-24" style="margin-left: 0.267em; margin-right: 0.267em;">+</span><span class="MJXp-mn" id="MJXp-Span-25">3</span><span class="MJXp-mi MJXp-italic" id="MJXp-Span-26">i</span></span></span></span><span id="MathJax-Element-2-Frame" class="mjx-chtml MathJax_CHTML MJXc-processed" tabindex="0" style="font-size: 127%;"><span id="MJXc-Node-19" class="mjx-math"><span id="MJXc-Node-20" class="mjx-mrow"><span id="MJXc-Node-21" class="mjx-mstyle"><span id="MJXc-Node-22" class="mjx-mrow" style="font-size: 144%;"><span id="MJXc-Node-23" class="mjx-texatom"><span id="MJXc-Node-24" class="mjx-mrow"><span id="MJXc-Node-25" class="mjx-msubsup"><span class="mjx-base" style="margin-right: -0.003em;"><span id="MJXc-Node-26" class="mjx-texatom"><span id="MJXc-Node-27" class="mjx-mrow"><span id="MJXc-Node-28" 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 class="mjx-sub" style="font-size: 70.7%; vertical-align: -0.212em; padding-right: 0.071em;"><span id="MJXc-Node-29" class="mjx-texatom" style=""><span id="MJXc-Node-30" class="mjx-mrow"><span id="MJXc-Node-31" class="mjx-mn"><span class="mjx-char MJXc-TeX-main-R" style="padding-top: 0.396em; padding-bottom: 0.347em;">2</span></span></span></span></span></span></span></span><span id="MJXc-Node-32" 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-33" class="mjx-mn MJXc-space3"><span class="mjx-char MJXc-TeX-main-R" style="padding-top: 0.396em; padding-bottom: 0.347em;">7</span></span><span id="MJXc-Node-34" 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-35" class="mjx-mn MJXc-space2"><span class="mjx-char MJXc-TeX-main-R" style="padding-top: 0.396em; padding-bottom: 0.347em;">3</span></span><span id="MJXc-Node-36" class="mjx-mi"><span class="mjx-char MJXc-TeX-math-I" style="padding-top: 0.445em; padding-bottom: 0.298em;">i</span></span></span></span></span></span></span><script type="math/tex" id="MathJax-Element-2">\Large {{z}_{2}}=7+3i</script>. Tì

Cho hai số phức z1=43iz1=43iz2=7+3iz2=7+3i. Tì

4.4/5

Tác giả: Thầy Tùng

Đăng ngày: 18 Aug 2022

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Câu hỏi:

Cho hai số phức z1=43iz1=43iz2=7+3iz2=7+3i. Tìm số phức z=z1z2z=z1z2.

Đáp án án đúng là: A

Lời giải chi tiết:

Chọn A

Ta có z=z1z2z=z1z2=(43i)(7+3i)=(43i)(7+3i)=36i=36i.