新GRE数学常用结论：代数与几何部分
<p> 1.正整数<span word="n">n</span>有奇数个因子,则<span word="n">n</span>为完全平方数</p><p> 2.因子个数特性：</p><p> 因子个数求解公式:将整数<span word="n">n</span>分解为质因子乘积形式,然后将每个质因子的幂分别加一相乘.即<span word="n">n</span>=<span word="xaybzc">xaybzc</span>，则因子个数=。</p><p> <span word="Eg">Eg</span>. 200=22255, 因子个数==12个</p><p> 3.整除特性：</p><p> 能被3整除的数,各位数字之和能被3整除.</p><p> 最后两位数构成的数，能够被4整除，该数可被4整除.</p><p> 最末位5或0，则该数能被5整除.</p><p> 最后三位数构成的数，能够被8整除，该数可被8整除.</p><p> 能被9整除的数,各位数的和能被9整除.</p><p> 4.多边形内角和=<span word="x">x</span>180</p><p> 5.菱形面积=1/2 <span word="x">x</span> 对角线乘积</p><p> 6.欧拉公式： 边数=面数+顶点数-2</p><p> 7.三角形余玄定理</p><p> <span word="C">C</span>2=<span word="A">A</span>2+<span word="B">B</span>2-2<span word="ABCOS">ABCOS</span>,为<span word="AB">AB</span>两条线间的夹角</p><p> 8.正弦定理:<span word="A">A</span>/<span word="SinA">SinA</span>=<span word="B">B</span>/<span word="SinB">SinB</span>=<span word="C">C</span>/<span word="SinC">SinC</span>=2<span word="R">R</span></p><p> 9.<span word="Y">Y</span>=<span word="k">k</span>1<span word="X">X</span>+<span word="B">B</span>1,<span word="Y">Y</span>=<span word="k">k</span>2<span word="X">X</span>+<span word="B">B</span>2，两线垂直的条件为<span word="K">K</span>1<span word="K">K</span>2=-1</p><p> 10.<span word="N">N</span>的阶乘公式:</p><p> <span word="N">N</span>!=123....<span word="N">N</span> 且规定0!=1 1!=1</p><p> <span word="Eg">Eg</span>:8!=12345678</p><p> 11. 熟悉一下根号2、3、5的值</p><p> <span word="sqrt">sqrt</span>=1.414 <span word="sqrt">sqrt</span>=1.732 <span word="sqrt">sqrt</span>=2.236</p><p> 12. ...2/3 <span word="as">as</span> <span word="many">many</span> <span word="A">A</span> <span word="as">as</span> <span word="B">B</span>: <span word="A">A</span>=2/3<span word="B">B</span></p><p> ...<span word="twice">twice</span> <span word="as">as</span> <span word="many">many</span>... <span word="A">A</span> <span word="as">as</span> <span word="B">B</span>: <span word="A">A</span>=2<span word="B">B</span></p>
页:
[1]