Cho số phức z thỏa mãn <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: 0em; margin-right: 0em;">(</span><span class="MJXp-mn" id="MJXp-Span-5">1</span><span class="MJXp-mo" id="MJXp-Span-6" style="margin-left: 0.267em; margin-right: 0.267em;">+</span><span class="MJXp-mi MJXp-italic" id="MJXp-Span-7">i</span><span class="MJXp-mo" id="MJXp-Span-8" style="margin-left: 0em; margin-right: 0em;">)</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">3</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">5</span><span class="MJXp-mi MJXp-italic" id="MJXp-Span-13">i</span></span></span></span><script type="math/tex" id="MathJax-Element-1">\Large z(1+i)=3-5 i</script>. Tính moodun của z $\Larg