GRE数学考生回忆（4）
<p> <span word="GRE">GRE</span>机经是很有效的<span word="GRE">GRE</span>备考资料，下面为大家讨论了一些新<span word="GRE">GRE</span>数学机经，一起来看一下吧。</p><p> 11、数列，<span word="a">a</span>_0=3， <span word="a">a</span>_=2<span word="a">a</span>_<span word="n">n</span> -1 求<span word="a">a</span>_20-<span word="a">a</span>_19。</p><p> <span word="a">a</span>1=3,<span word="an">an</span>+1=2<span word="an">an</span>-1,<span word="a">a</span>20-<span word="a">a</span>19=?选2^19</p><p> <span word="a">a</span>_20-<span word="a">a</span>_19=-1-</p><p> =-1</p><p> =-2</p><p> =-4 ........ =<span word="a">a</span>_1-</p><p> =<span word="a">a</span>_0- 已知<span word="a">a</span>_0=3 所以<span word="a">a</span>_20-<span word="a">a</span>_19 = =2^20 已知<span word="a">a</span>_1=3 所以<span word="a">a</span>_20-<span word="a">a</span>_19 = =2^19</p><p> 12、<span word="DS">DS</span>：两个连续正整数<span word="list">list</span>，最小数相等，问两个<span word="list">list</span>的<span word="mediant">mediant</span>的差。</p><p> 条件 1) 那个相等的最小数是10</p><p> 2) <span word="list">list</span>1有9个数，<span word="list">list</span>2有10个数。</p><p> 条件1)不知道两个<span word="list">list</span>中各自有几个数，无法求得<span word="mediant">mediant</span>差值</p><p> 条件2)设 两个<span word="list">list</span>最小数= <span word="N">N</span></p><p> <span word="List">List</span>1的中位数= <span word="N">N</span>+5</p><p> <span word="List">List</span>2的中位数=/2=<span word="N">N</span>+4.5</p><p> <span word="mediant">mediant</span>差值= <span word="N">N</span>+5-<span word="N">N</span>-4.5=0.5 确定 选<span word="B">B</span></p><p> 13 、说冰山，水面上部分的质量是全部质量的1/7~1/8，问水面上部分的质量是水面下部分质量的多少? /~/= 1/7 ~ 1/6</p><p> 14、<span word="DS">DS</span>，说有<span word="positive">positive</span> <span word="number">number</span> <span word="y">y</span>，能不能知道<span word="y">y</span>四舍五入是多少?条件1) 4<span word="y">y</span>的四舍五入是6</p><p> 2) <span word="y">y</span>/2的四舍五入是1</p><p> 条件1)4<span word="y">y</span>6可知：5.56.4 则：1.3751.6 无法确定</p>
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