Tính mô đun của 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="1.2em"><mi>z</mi><mo>=</mo><mstyle displaystyle="true" scriptlevel="0"><mfrac><mrow><mn>4</mn><mo>&#x2212;</mo><mn>3</mn><mi>i</mi></mrow><mrow><mn>1</mn><mo>+</mo><mn>2</mn><mi>i</mi></mrow></mfrac></mstyle></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: 120%;"><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-mstyle MJXc-space3"><span id="MJXc-Node-8" class="mjx-mrow"><span id="MJXc-Node-9" class="mjx-mfrac"><span class="mjx-box MJXc-stacked" style="width: 2.767em; padding: 0px 0.12em;"><span class="mjx-numerator" style="width: 2.767em; top: -1.379em;"><span id="MJXc-Node-10" class="mjx-mrow"><span id="MJXc-Node-11" class="mjx-mn"><span class="mjx-char MJXc-TeX-main-R" style="padding-top: 0.396em; padding-bottom: 0.347em;">4</span></span><span id="MJXc-Node-12" 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-13" 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-14" 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 class="mjx-denominator" style="width: 2.767em; bottom: -0.793em;"><span id="MJXc-Node-15" class="mjx-mrow"><span id="MJXc-Node-16" class="mjx-mn"><span class="mjx-char MJXc-TeX-main-R" style="padding-top: 0.396em; padding-bottom: 0.347em;">1</span></span><span id="MJXc-Node-17" 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-18" 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-19" 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 class="mjx-line" style="border-bottom: 1.5px solid; top: -0.281em; width: 2.767em;"></span></span><span class="mjx-vsize" style="height: 2.171em; vertical-align: -0.793em;"></span></span></span></span></span></span></span></span><span class="MJX_Assistive_MathML" role="presentation"><math xmlns="http://www.w3.org/1998/Math/MathML"><mstyle mathsize="1.2em"><mi>z</mi><mo>=</mo><mstyle displaystyle="true" scriptlevel="0"><mfrac><mrow><mn>4</mn><mo>−</mo><mn>3</mn><mi>i</mi></mrow><mrow><mn>1</mn><mo>+</mo><mn>2</mn><mi>i</mi></mrow></mfrac></mstyle></mstyle></math></span></span><script type="math/tex" id="MathJax-Element-1">\large z = \dfrac {4 - 3i}{1 + 2i}</script> $\large \

Tính mô đun của số phức z=43i1+2i $\large \

4.5/5

Tác giả: Thầy Tùng

Đăng ngày: 18 Aug 2022

Lưu về Facebook:

Câu hỏi:

Tính mô đun của số phức z=43i1+2i

Đáp án án đúng là: A

Lời giải chi tiết:

Ta có z=43i1+2i=25115i
Suy ra |z|=(25)2+(115)2=5