新gre数学考点介绍：Substitution
<p> 新<span word="gre">gre</span>考试实施以来，不仅对写作部分茫然不知所措，就连我们所擅长的数学也甚是担忧，相信这其中的原因还是由于考生在新<span word="gre">gre</span>数学复习时没有把基础打牢。如果新版<span word="gre">gre</span>数学基本考点都没有复习到，如何能拿到分数呢?所以说，想要新版<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> 今天针对新版<span word="gre">gre</span>数学复习，小编给大家整理的是关于<span word="Substitution">Substitution</span>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，突破新版<span word="gre">gre</span>数学难的困境。</p><p> <span word="Substitution">Substitution</span></p><p> <span word="Substitution">Substitution</span> is a method where one or more variables in an expression is replaced by numbers or another set of variables.To evaluate an expression specific numbers are used as substitute. To express in terms of another set of variables, variables are replaced by the new set of variables.</p><p> <span word="Example">Example</span>:</p><p> <span word="If">If</span> <span word="x">x</span>=3, <span word="then">then</span> 2<span word="x">x</span>2+4<span word="x">x</span>+1 <span word="can">can</span> <span word="be">be</span> <span word="evaluated">evaluated</span> <span word="by">by</span> <span word="substituting">substituting</span> 3 <span word="for">for</span> <span word="x">x</span>.</p><p> <span word="Replacing">Replacing</span> <span word="all">all</span> <span word="x">x</span> <span word="by">by</span> 3, <span word="we">we</span> <span word="get">get</span> 232+43+1=31.</p><p> <span word="If">If</span> <span word="x">x</span>=2+<span word="y">y</span>, <span word="then">then</span> <span word="x">x</span>2-3 <span word="can">can</span> <span word="be">be</span> <span word="expressed">expressed</span> <span word="in">in</span> <span word="terms">terms</span> <span word="of">of</span> <span word="y">y</span> <span word="by">by</span> <span word="replacing">replacing</span> <span word="all">all</span> <span word="x">x</span> <span word="by">by</span> :2-3=<span word="y">y</span>2+4<span word="y">y</span>+1.</p><p> <span word="Remember">Remember</span>:</p><p> <span word="Do">Do</span> <span word="not">not</span> <span word="forget">forget</span> <span word="to">to</span> <span word="replace">replace</span> <span word="all">all</span> <span word="occurrences">occurrences</span> <span word="of">of</span> <span word="the">the</span> <span word="variable">variable</span>.</p><p> <span word="After">After</span> <span word="substitution">substitution</span> <span word="the">the</span> <span word="variable">variable</span> <span word="does">does</span> <span word="not">not</span> <span word="appear">appear</span> <span word="anywhere">anywhere</span> <span word="in">in</span> <span word="the">the</span> <span word="expression">expression</span>.</p>
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