新gre数学考点介绍：并集和交集
<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> <span word="Intersection">Intersection</span> <span word="of">of</span> <span word="Sets">Sets</span></p><p> <span word="Intersection">Intersection</span> <span word="of">of</span> <span word="two">two</span> <span word="sets">sets</span> <span word="is">is</span> <span word="another">another</span> <span word="set">set</span> <span word="with">with</span> <span word="only">only</span> <span word="the">the</span> <span word="members">members</span> <span word="that">that</span> <span word="are">are</span> <span word="in">in</span> <span word="both">both</span> <span word="sets">sets</span>. <span word="If">If</span> <span word="the">the</span> <span word="two">two</span> <span word="sets">sets</span> <span word="do">do</span> <span word="not">not</span> <span word="share">share</span> <span word="any">any</span> <span word="common">common</span> <span word="member">member</span>, <span word="the">the</span> <span word="intersection">intersection</span> <span word="is">is</span> <span word="the">the</span> <span word="empty">empty</span> <span word="set">set</span> <span word="with">with</span> <span word="no">no</span> <span word="member">member</span>.</p><p> <span word="Example">Example</span>:</p><p> <span word="Intersection">Intersection</span> <span word="of">of</span> {1,2,3} <span word="and">and</span> {2,3,5} <span word="is">is</span> <span word="the">the</span> <span word="set">set</span> {2,3}.</p><p> <span word="Intersection">Intersection</span> <span word="of">of</span> <span word="the">the</span> <span word="set">set</span> <span word="with">with</span> <span word="all">all</span> <span word="primes">primes</span> <span word="and">and</span> <span word="the">the</span> <span word="set">set</span> <span word="with">with</span> <span word="all">all</span> <span word="even">even</span> <span word="numbers">numbers</span> <span word="is">is</span> <span word="the">the</span> <span word="set">set</span> {2} <span word="since">since</span> <span word="only">only</span> 2 <span word="is">is</span> <span word="both">both</span> <span word="even">even</span> <span word="and">and</span> <span word="prime">prime</span>.</p><p> <span word="Intersection">Intersection</span> <span word="of">of</span> {1,2,3} <span word="and">and</span> {4,5,6} <span word="is">is</span> <span word="the">the</span> <span word="empty">empty</span> <span word="set">set</span> {}.</p><p> <span word="Remember">Remember</span>:</p><p> <span word="Intersection">Intersection</span> <span word="contains">contains</span> <span word="only">only</span> <span word="the">the</span> <span word="common">common</span> <span word="members">members</span>.</p><p> <span word="Two">Two</span> <span word="sets">sets</span> <span word="are">are</span> <span word="disjoint">disjoint</span> <span word="if">if</span> <span word="they">they</span> <span word="have">have</span> <span word="no">no</span> <span word="member">member</span> <span word="in">in</span> <span word="common">common</span>, <span word="that">that</span> <span word="is">is</span> <span word="they">they</span> <span word="have">have</span> <span word="an">an</span> <span word="empty">empty</span> <span word="intersection">intersection</span>.</p><p> <span word="Union">Union</span> <span word="of">of</span> <span word="Sets">Sets</span></p><p> <span word="Union">Union</span> <span word="of">of</span> <span word="two">two</span> <span word="sets">sets</span> <span word="is">is</span> <span word="another">another</span> <span word="set">set</span> <span word="with">with</span> <span word="all">all</span> <span word="the">the</span> <span word="members">members</span> <span word="from">from</span> <span word="both">both</span> <span word="sets">sets</span>.</p><p> <span word="Example">Example</span>:</p><p> <span word="Union">Union</span> <span word="of">of</span> {2,3,5} <span word="and">and</span> {1,3,4} <span word="is">is</span> <span word="the">the</span> <span word="set">set</span> {1,2,3,4,5}.</p><p> <span word="Union">Union</span> <span word="of">of</span> {1,2,1} <span word="and">and</span> {1,2} <span word="is">is</span> <span word="the">the</span> <span word="set">set</span> {1,2,1}.</p>
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