Код:
<div class="MathJax_Display" role="textbox" aria-readonly="true" style="text-align: center">
<span class="MathJax" id="MathJax-Element-2-Frame" style="">
<nobr>
<span class="math" id="MathJax-Span-53">
<span style="display: inline-block; position: relative; height: 0px; font-size: 116%; width: 281px">
<span style="position: absolute; clip: rect(2.09em, 1000em, 5.61em, -0.25em); top: -4.2em; left: 0em">
<span class="mrow" id="MathJax-Span-54" style="">
<span class="msubsup" id="MathJax-Span-55">
<span style="display: inline-block; position: relative; height: 0px; width: 5.52em">
<span style="position: absolute; clip: rect(2.08em, 1000em, 5.4em, -0.25em); top: -3.99em; left: 0em">
<span class="mfenced" id="MathJax-Span-56" style="">
<span class="mo" id="MathJax-Span-75" style="vertical-align: 0em">
<span style="font-family: "MathJax_Size4"">(</span>
</span>
<span class="mrow" id="MathJax-Span-58">
<span class="munderover" id="MathJax-Span-59">
<span style="display: inline-block; position: relative; height: 0px; width: 1.46em">
<span style="position: absolute; clip: rect(2.88em, 1000em, 4.6em, -0.43em); top: -3.99em; left: 0em">
<span class="mo" id="MathJax-Span-60" style="font-family: "MathJax_Size2"; vertical-align: 0em">∑</span>
<span style="display: inline-block; width: 0px; height: 3.99em"></span>
</span>
<span style="position: absolute; clip: rect(3.34em, 1000em, 4.26em, -0.45em); top: -2.88em; left: 0.08em">
<span class="texatom" id="MathJax-Span-62" style="">
<span class="mrow" id="MathJax-Span-63">
<span class="mi" id="MathJax-Span-64" style="font-size: 70.7%; font-family: "MathJax_Math-italic"">k</span>
<span class="mo" id="MathJax-Span-65" style="font-size: 70.7%; font-family: "MathJax_Main"">=</span>
<span class="mn" id="MathJax-Span-66" style="font-size: 70.7%; font-family: "MathJax_Main"">1</span>
</span>
</span>
<span style="display: inline-block; width: 0px; height: 3.99em"></span>
</span>
<span style="position: absolute; clip: rect(3.41em, 1000em, 4.16em, -0.47em); top: -5.14em; left: 0.51em">
<span class="mi" id="MathJax-Span-67" style="font-size: 70.7%; font-family: "MathJax_Math-italic"">n</span>
<span style="display: inline-block; width: 0px; height: 3.99em"></span>
</span>
</span>
</span>
<span class="msubsup" id="MathJax-Span-68" style="padding-left: 0.17em">
<span style="display: inline-block; position: relative; height: 0px; width: 0.99em">
<span style="position: absolute; clip: rect(3.38em, 1000em, 4.16em, -0.45em); top: -3.99em; left: 0em">
<span class="mi" id="MathJax-Span-69" style="font-family: "MathJax_Math-italic"">a</span>
<span style="display: inline-block; width: 0px; height: 3.99em"></span>
</span>
<span style="position: absolute; top: -3.84em; left: 0.54em">
<span class="mi" id="MathJax-Span-70" style="font-size: 70.7%; font-family: "MathJax_Math-italic"">k</span>
<span style="display: inline-block; width: 0px; height: 3.99em"></span>
</span>
</span>
</span>
<span class="msubsup" id="MathJax-Span-71">
<span style="display: inline-block; position: relative; height: 0px; width: 0.88em">
<span style="position: absolute; clip: rect(3.13em, 1000em, 4.16em, -0.44em); top: -3.99em; left: 0em">
<span class="mi" id="MathJax-Span-72" style="font-family: "MathJax_Math-italic"">b</span>
<span style="display: inline-block; width: 0px; height: 3.99em"></span>
</span>
<span style="position: absolute; top: -3.84em; left: 0.43em">
<span class="mi" id="MathJax-Span-73" style="font-size: 70.7%; font-family: "MathJax_Math-italic"">k</span>
<span style="display: inline-block; width: 0px; height: 3.99em"></span>
</span>
</span>
</span>
</span>
<span class="mo" id="MathJax-Span-76" style="vertical-align: 0em">
<span style="font-family: "MathJax_Size4"">)</span>
</span>
</span>
<span style="display: inline-block; width: 0px; height: 3.99em"></span>
</span>
<span style="position: absolute; top: -5.46em; left: 5.07em">
<span class="mn" id="MathJax-Span-77" style="font-size: 70.7%; font-family: "MathJax_Main"">2</span>
<span style="display: inline-block; width: 0px; height: 3.99em"></span>
</span>
</span>
</span>
<span class="mo" id="MathJax-Span-78" style="font-family: "MathJax_Main"; padding-left: 0.28em">≤</span>
<span class="mfenced" id="MathJax-Span-79" style="padding-left: 0.28em">
<span class="mo" id="MathJax-Span-80" style="vertical-align: 0em">
<span style="font-family: "MathJax_Size4"">(</span>
</span>
<span class="mrow" id="MathJax-Span-81">
<span class="munderover" id="MathJax-Span-82">
<span style="display: inline-block; position: relative; height: 0px; width: 1.46em">
<span style="position: absolute; clip: rect(2.88em, 1000em, 4.6em, -0.43em); top: -3.99em; left: 0em">
<span class="mo" id="MathJax-Span-83" style="font-family: "MathJax_Size2"; vertical-align: 0em">∑</span>
<span style="display: inline-block; width: 0px; height: 3.99em"></span>
</span>
<span style="position: absolute; clip: rect(3.34em, 1000em, 4.26em, -0.45em); top: -2.88em; left: 0.08em">
<span class="texatom" id="MathJax-Span-84" style="">
<span class="mrow" id="MathJax-Span-85">
<span class="mi" id="MathJax-Span-86" style="font-size: 70.7%; font-family: "MathJax_Math-italic"">k</span>
<span class="mo" id="MathJax-Span-87" style="font-size: 70.7%; font-family: "MathJax_Main"">=</span>
<span class="mn" id="MathJax-Span-88" style="font-size: 70.7%; font-family: "MathJax_Main"">1</span>
</span>
</span>
<span style="display: inline-block; width: 0px; height: 3.99em"></span>
</span>
<span style="position: absolute; clip: rect(3.41em, 1000em, 4.16em, -0.47em); top: -5.14em; left: 0.51em">
<span class="mi" id="MathJax-Span-89" style="font-size: 70.7%; font-family: "MathJax_Math-italic"">n</span>
<span style="display: inline-block; width: 0px; height: 3.99em"></span>
</span>
</span>
</span>
<span class="msubsup" id="MathJax-Span-90" style="padding-left: 0.17em">
<span style="display: inline-block; position: relative; height: 0px; width: 0.99em">
<span style="position: absolute; clip: rect(3.38em, 1000em, 4.16em, -0.45em); top: -3.99em; left: 0em">
<span class="mi" id="MathJax-Span-91" style="font-family: "MathJax_Math-italic"">a</span>
<span style="display: inline-block; width: 0px; height: 3.99em"></span>
</span>
<span style="position: absolute; clip: rect(3.35em, 1000em, 4.15em, -0.45em); top: -4.33em; left: 0.54em">
<span class="mn" id="MathJax-Span-92" style="font-size: 70.7%; font-family: "MathJax_Main"">2</span>
<span style="display: inline-block; width: 0px; height: 3.99em"></span>
</span>
<span style="position: absolute; clip: rect(3.34em, 1000em, 4.16em, -0.45em); top: -3.66em; left: 0.54em">
<span class="mi" id="MathJax-Span-93" style="font-size: 70.7%; font-family: "MathJax_Math-italic"">k</span>
<span style="display: inline-block; width: 0px; height: 3.99em"></span>
</span>
</span>
</span>
</span>
<span class="mo" id="MathJax-Span-94" style="vertical-align: 0em">
<span style="font-family: "MathJax_Size4"">)</span>
</span>
</span>
<span class="mfenced" id="MathJax-Span-95">
<span class="mo" id="MathJax-Span-96" style="vertical-align: 0em">
<span style="font-family: "MathJax_Size4"">(</span>
</span>
<span class="mrow" id="MathJax-Span-97">
<span class="munderover" id="MathJax-Span-98">
<span style="display: inline-block; position: relative; height: 0px; width: 1.46em">
<span style="position: absolute; clip: rect(2.88em, 1000em, 4.6em, -0.43em); top: -3.99em; left: 0em">
<span class="mo" id="MathJax-Span-99" style="font-family: "MathJax_Size2"; vertical-align: 0em">∑</span>
<span style="display: inline-block; width: 0px; height: 3.99em"></span>
</span>
<span style="position: absolute; clip: rect(3.34em, 1000em, 4.26em, -0.45em); top: -2.88em; left: 0.08em">
<span class="texatom" id="MathJax-Span-100" style="">
<span class="mrow" id="MathJax-Span-101">
<span class="mi" id="MathJax-Span-102" style="font-size: 70.7%; font-family: "MathJax_Math-italic"">k</span>
<span class="mo" id="MathJax-Span-103" style="font-size: 70.7%; font-family: "MathJax_Main"">=</span>
<span class="mn" id="MathJax-Span-104" style="font-size: 70.7%; font-family: "MathJax_Main"">1</span>
</span>
</span>
<span style="display: inline-block; width: 0px; height: 3.99em"></span>
</span>
<span style="position: absolute; clip: rect(3.41em, 1000em, 4.16em, -0.47em); top: -5.14em; left: 0.51em">
<span class="mi" id="MathJax-Span-105" style="font-size: 70.7%; font-family: "MathJax_Math-italic"">n</span>
<span style="display: inline-block; width: 0px; height: 3.99em"></span>
</span>
</span>
</span>
<span class="msubsup" id="MathJax-Span-106" style="padding-left: 0.17em">
<span style="display: inline-block; position: relative; height: 0px; width: 0.88em">
<span style="position: absolute; clip: rect(3.13em, 1000em, 4.16em, -0.44em); top: -3.99em; left: 0em">
<span class="mi" id="MathJax-Span-107" style="font-family: "MathJax_Math-italic"">b</span>
<span style="display: inline-block; width: 0px; height: 3.99em"></span>
</span>
<span style="position: absolute; clip: rect(3.35em, 1000em, 4.15em, -0.45em); top: -4.41em; left: 0.43em">
<span class="mn" id="MathJax-Span-108" style="font-size: 70.7%; font-family: "MathJax_Main"">2</span>
<span style="display: inline-block; width: 0px; height: 3.99em"></span>
</span>
<span style="position: absolute; clip: rect(3.34em, 1000em, 4.16em, -0.45em); top: -3.74em; left: 0.43em">
<span class="mi" id="MathJax-Span-109" style="font-size: 70.7%; font-family: "MathJax_Math-italic"">k</span>
<span style="display: inline-block; width: 0px; height: 3.99em"></span>
</span>
</span>
</span>
</span>
<span class="mo" id="MathJax-Span-110" style="vertical-align: 0em">
<span style="font-family: "MathJax_Size4"">)</span>
</span>
</span>
</span>
<span style="display: inline-block; width: 0px; height: 4.2em"></span>
</span>
</span>
<span style="border-left-color: currentColor; border-left-width: 0em; border-left-style: solid; display: inline-block; overflow-x: hidden; overflow-y: hidden; width: 0px; height: 3.83em; vertical-align: -1.51em"></span>
</span>
</nobr>
</span>
</div>