新GRE数学考点：Combinations of Choices
<p> 今天针对新<span word="gre">gre</span>数学复习，小编给大家整理的是关于排列、组合的相关内容，这些概念在考试中一定会考到的。希望考生能再接再厉，取得一个好成绩，突破新<span word="gre">gre</span>数学难的困境。</p><p> <span word="Combinations">Combinations</span> <span word="of">of</span> <span word="Choices">Choices</span></p><p> <span word="If">If</span> <span word="there">there</span> <span word="are">are</span> <span word="n">n</span> <span word="choices">choices</span> <span word="for">for</span> <span word="one">one</span> <span word="type">type</span> <span word="and">and</span> <span word="m">m</span> <span word="choices">choices</span> <span word="for">for</span> <span word="second">second</span> <span word="type">type</span>, <span word="then">then</span> <span word="number">number</span> <span word="of">of</span> <span word="combinations">combinations</span> <span word="for">for</span> <span word="both">both</span> <span word="types">types</span> <span word="is">is</span> <span word="the">the</span> <span word="product">product</span> <span word="of">of</span> <span word="choices">choices</span>:<span word="nm">nm</span>.</p><p> <span word="Example">Example</span>:</p><p> <span word="If">If</span> <span word="there">there</span> <span word="are">are</span> 3 <span word="kinds">kinds</span> <span word="of">of</span> <span word="breads">breads</span> <span word="to">to</span> <span word="choose">choose</span> <span word="from">from</span> <span word="and">and</span> 4 <span word="kinds">kinds</span> <span word="of">of</span> <span word="meats">meats</span>, <span word="then">then</span> <span word="we">we</span> <span word="can">can</span> <span word="make">make</span> 34=12 <span word="different">different</span> <span word="sandwiches">sandwiches</span>.</p><p> <span word="If">If</span> <span word="an">an</span> <span word="alphabet">alphabet</span> <span word="has">has</span> 26 <span word="letters">letters</span>, <span word="then">then</span> <span word="the">the</span> <span word="number">number</span> <span word="of">of</span> <span word="possible">possible</span> 2 <span word="letter">letter</span> <span word="word">word</span> <span word="is">is</span> 2626=676.<span word="All">All</span> <span word="of">of</span> <span word="them">them</span> <span word="may">may</span> <span word="not">not</span> <span word="be">be</span> <span word="vaild">vaild</span> <span word="words">words</span>.</p><p> <span word="Remember">Remember</span>:</p><p> <span word="Do">Do</span> <span word="not">not</span> <span word="add">add</span> <span word="the">the</span> <span word="choices">choices</span> <span word="to">to</span> <span word="get">get</span> <span word="the">the</span> <span word="total">total</span> <span word="combinations">combinations</span>.</p><p> <span word="The">The</span> <span word="product">product</span> <span word="rule">rule</span> <span word="can">can</span> <span word="be">be</span> <span word="applied">applied</span> <span word="to">to</span> <span word="more">more</span> <span word="than">than</span> <span word="two">two</span> <span word="types">types</span> <span word="of">of</span> <span word="choices">choices</span>: <span word="if">if</span> <span word="there">there</span> <span word="are">are</span> 3 <span word="kinds">kinds</span> <span word="of">of</span> <span word="breads">breads</span>, 4 <span word="kinds">kinds</span> <span word="of">of</span> <span word="meats">meats</span>, <span word="and">and</span> 6 <span word="kinds">kinds</span> <span word="of">of</span> <span word="cheeses">cheeses</span>, <span word="then">then</span> <span word="we">we</span> <span word="can">can</span> <span word="make">make</span> 346=72 <span word="different">different</span> <span word="sandwiches">sandwiches</span>.</p><p> 俗话说：工欲善其事必先利其器。有一部分考生认为新<span word="GRE">GRE</span>数学具有一定的难度，这其中的原因是由于考生在复习时没有把新<span word="gre">gre</span>数学的基础打牢。想要新<span word="gre">gre</span>数学考好，复习的时候一定要把基本概念和重要考点都弄扎实。</p><p> </p><p> </p>
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