Nghiệm của phương trình <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-msubsup" id="MJXp-Span-3"><span class="MJXp-mn" id="MJXp-Span-4" style="margin-right: 0.05em;">3</span><span class="MJXp-mrow MJXp-script" id="MJXp-Span-5" style="vertical-align: 0.5em;"><span class="MJXp-mn" id="MJXp-Span-6">2</span><span class="MJXp-mi MJXp-italic" id="MJXp-Span-7">x</span><span class="MJXp-mo" id="MJXp-Span-8">+</span><span class="MJXp-mn" id="MJXp-Span-9">1</span></span></span><span class="MJXp-mo" id="MJXp-Span-10" style="margin-left: 0.333em; margin-right: 0.333em;">=</span><span class="MJXp-mstyle" id="MJXp-Span-11"><span class="MJXp-mfrac" id="MJXp-Span-12" style="vertical-align: 0.25em;"><span class="MJXp-box"><span class="MJXp-mn" id="MJXp-Span-13">1</span></span><span class="MJXp-box" style="margin-top: -0.9em;"><span class="MJXp-denom"><span><span class="MJXp-rule" style="height: 1em; border-top: none; border-bottom: 1px solid; margin: 0.1em 0px;"></span></span><span><span class="MJXp-box"><span class="MJXp-mn" id="MJXp-Span-14">27</span></span></span></span></span></span></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 3^{2x+1}=\dfrac{1}{27}</script> là A. x = 2 B.