Cho số thực x thỏa mãn <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="1.44em"><msup><mn>2</mn><mrow class="MJX-TeXAtom-ORD"><msup><mi>x</mi><mrow class="MJX-TeXAtom-ORD"><mn>2</mn></mrow></msup></mrow></msup><mo>&#x22C5;</mo><msup><mn>3</mn><mrow class="MJX-TeXAtom-ORD"><mi>x</mi><mo>+</mo><mn>1</mn></mrow></msup><mo>=</mo><mn>1</mn></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: 144%;"><span id="MJXc-Node-5" class="mjx-msubsup"><span class="mjx-base"><span id="MJXc-Node-6" 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 class="mjx-sup" style="font-size: 70.7%; vertical-align: 0.591em; padding-left: 0px; padding-right: 0.071em;"><span id="MJXc-Node-7" class="mjx-texatom" style=""><span id="MJXc-Node-8" class="mjx-mrow"><span id="MJXc-Node-9" class="mjx-msubsup"><span class="mjx-base"><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;">x</span></span></span><span class="mjx-sup" style="font-size: 70.7%; vertical-align: 0.513em; padding-left: 0px; 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;">2</span></span></span></span></span></span></span></span></span></span><span id="MJXc-Node-14" class="mjx-mo MJXc-space2"><span class="mjx-char MJXc-TeX-main-R" style="padding-top: 0.002em; padding-bottom: 0.298em;">⋅</span></span><span id="MJXc-Node-15" class="mjx-msubsup MJXc-space2"><span class="mjx-base"><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;">3</span></span></span><span class="mjx-sup" style="font-size: 70.7%; vertical-align: 0.59em; padding-left: 0px; padding-right: 0.071em;"><span id="MJXc-Node-17" class="mjx-texatom" style=""><span id="MJXc-Node-18" class="mjx-mrow"><span id="MJXc-Node-19" class="mjx-mi"><span class="mjx-char MJXc-TeX-math-I" style="padding-top: 0.199em; padding-bottom: 0.298em;">x</span></span><span id="MJXc-Node-20" class="mjx-mo"><span class="mjx-char MJXc-TeX-main-R" style="padding-top: 0.298em; padding-bottom: 0.445em;">+</span></span><span id="MJXc-Node-21" 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 id="MJXc-Node-22" 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-23" class="mjx-mn MJXc-space3"><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 class="MJX_Assistive_MathML" role="presentation"><math xmlns="http://www.w3.org/1998/Math/MathML"><mstyle mathsize="1.44em"><msup><mn>2</mn><mrow class="MJX-TeXAtom-ORD"><msup><mi>x</mi><mrow class="MJX-TeXAtom-ORD"><mn>2</mn></mrow></msup></mrow></msup><mo>⋅</mo><msup><mn>3</mn><mrow class="MJX-TeXAtom-ORD"><mi>x</mi><mo>+</mo><mn>1</mn></mrow></msup><mo>=</mo><mn>1</mn></mstyle></math></span></span><script type="math/tex" id="MathJax-Element-1">\Large 2^{x^{2}} \cdot 3^{x+1}=1</script>. Mệnh đề nào

Cho số thực x thỏa mãn 2x23x+1=1. Mệnh đề nào

4.7/5

Tác giả: Thầy Tùng

Đăng ngày: 18 Aug 2022

Lưu về Facebook:

Câu hỏi:

Cho số thực x thỏa mãn 2x23x+1=1. Mệnh đề nào dưới đây đúng?

Đáp án án đúng là: A

Lời giải chi tiết:

Chọn A

Ta có 2x23x+1=1log2(2x23x+1)=log21 log22x2+log23x+1=0x2+(x+1)log23=0