[10-20 18:11:12] 来源:http://www.67xuexi.com 高一数学 阅读:85886次
5.化简23-610-43+22得()
A.3+2B.2+3
C.1+22D.1+23
解析:选A.原式=23-610-4?2+1?
=23-622-42+?2?2=23-6?2-2?
=9+62+2=3+2.Xkb1.com
6.设a12-a-12=m,则a2+1a=()
A.m2-2B.2-m2
C.m2+2D.m2
解析:选C.将a12-a-12=m平方得(a12-a-12)2=m2,即a-2+a-1=m2,所以a+a-1=m2+2,即a+1a=m2+2?a2+1a=m2+2.
7.根式a-a化成分数指数幂是________.
解析:∵-a≥0,∴a≤0,
∴a-a=-?-a?2?-a?=-?-a?3=-(-a)32.
答案:-(-a)32
8.化简11+62+11-62=________.
解析:11+62+11-62=?3+2?2+?3-2?2=3+2+(3-2)=6.
答案:6
9.化简(3+2)2010?(3-2)2011=________.
解析:(3+2)2010?(3-2)2011
=[(3+2)(3-2)]2010?(3-2)
=12010?(3-2)=3-2.
答案:3-2
10.化简求值:
(1)0.064-13-(-18)0+1634+0.2512;
(2)a-1+b-1?ab?-1(a,b≠0).
解:(1)原式=(0.43)-13-1+(24)34+(0.52)12
=0.4-1-1+8+12
=52+7+12=10.
(2)原式=1a+1b1ab=a+bab1ab=a+b.
11.已知x+y=12,xy=9,且x
解:x12-y12x12+y12=?x+y?-2?xy?12x-y.
∵x+y=12,xy=9,
则有(x-y)2=(x+y)2-4xy=108.
又x
代入原式可得结果为-33.