小学奥数举一反三6年级B版第五周简便运算(四)第五题
1个回答
5题
=（1/1*3 *2002+1/3*5 * 2002+1/5*7 *2002+1/9*11 * 2002）*1/2
=（1-1/3+1/3-1/5+1/5-1/7+1/7-1/11）*2002*1/2
=（1-1/11）*2002*1/2
=10/11*2002 / 2
=910
提高卷
1.
=1/3-1/4+1/4-1/5+1/5-1/6.+1/9-1/10
=1/3-1/10
=7/30
2.
=1-1/4+1/4-1/5+1/5-1/6+1/6-1/7+1/7-1/8
=1-1/8
=7/8
3.
=(1-1/5+1/5-1/9+1/9-1/13+.+1/55-1/59)*1/4
=(1-1/59)*1/4
=29/118
4.
设(1+1/3+1/5+1/7)为a ,(1/3+1/5+1/7)为b
a*(b+1/9)-(a+1/9)*b
=ab+1/9a-ab-1/9b
=1/9(a-b)
=1/9
5.
=5/14*(5/6-7/12+9/20)
=5/14*[1/2+1/3-(1/3+1/4)+1/4+1/5]
=5/14*(1/2+1/3-1/3-1/4+1/4+1/5)
=5/14*7/10
=1/4
6.
=1/1*3 + 1/3*5 + 1/5*7 + 1/7*9 + 1/9*11
=(1-1/3+1/3-1/5+1/5-1/7+1/7-1/9+1/9-1/11)*1/2
=(1-1/11)*1/2
=5/11
