新版gre考试：习题解答
<p> 由于美国数学基础教育的难度增加，<span word="gre">gre</span>数学考试也越来越难，所以新版<span word="gre">gre</span>考试数学部分不能轻视，以下是小编为大家搜索整理的有关新版<span word="gre">gre</span>考试数学中常考知识：代数和几何部分。</p><p> 1：还有数列题：<span word="a">a</span>1=2，<span word="a">a</span>2=6，<span word="an">an</span>=<span word="an">an</span>-1/<span word="an">an</span>-2，求<span word="a">a</span>150.</p><p> 解答: <span word="an">an</span>=<span word="an">an</span>-1/<span word="an">an</span>-2,所以<span word="an">an</span>-1=<span word="an">an</span>-2/<span word="an">an</span>-3,带入前式得<span word="an">an</span>=1/<span word="an">an</span>-3,然后再拆一遍得到<span word="an">an</span>=<span word="an">an</span>-6,也就是说,这个数列是以6为周期的,则<span word="a">a</span>150=<span word="a">a</span>144=...=<span word="a">a</span>6,利用<span word="a">a</span>1,<span word="a">a</span>2可以计算出<span word="a">a</span>6=1/3.</p><p> 如果实在想不到这个方法,可以写几项看看很快就会发现<span word="a">a</span>150=<span word="a">a</span>144,大胆推测该数列是以6为周期得,然后写出<span word="a">a</span>1-<span word="a">a</span>13,不难发现<span word="a">a</span>6=<span word="a">a</span>12,<span word="a">a</span>7=<span word="a">a</span>13,然后那,稍微数数,就可以知道<span word="a">a</span>150=<span word="a">a</span>6了,同样计算得1/3.</p><p> 2：问摄氏升高30度华氏升高的度数与62比大小.</p><p> <span word="key">key</span>:<span word="F">F</span>=309/5=5462</p><p> 3：那道费波拉契数列的题:已知,<span word="a">a</span>1=1 <span word="a">a</span>2=1 <span word="an">an</span>=<span word="an">an</span>-1+<span word="an">an</span>-2 ，问<span word="a">a</span>1,<span word="a">a</span>2,<span word="a">a</span>3,<span word="a">a</span>6四项的平均数和<span word="a">a</span>1,<span word="a">a</span>3,<span word="a">a</span>4,<span word="a">a</span>5四项的平均数大小比较。</p><p> 解答:费波契那数列就是第三项是前两项的和,依此类推得到<span word="a">a</span>1-<span word="a">a</span>6为:</p><p> 1 1 2 3 5 8 13 21 <span word="a">a</span>1+<span word="a">a</span>2+<span word="a">a</span>3+<span word="a">a</span>6=12, <span word="a">a</span>1+<span word="a">a</span>3+<span word="a">a</span>4+<span word="a">a</span>5=11,所以为大于.</p><p> 4：满足<span word="x">x</span>^2+<span word="y">y</span>^2=100的整数对有多少?</p><p> <span word="key">key</span>: 按照<span word="X">X</span>的可能情况顺序写出:</p><p> <span word="X">X</span>= <span word="Y">Y</span>=</p><p> 1 1-9</p>
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