13-14-15-16-哪种好 牌子同款推荐
简便运算题1+2+3+4 - 5 - 6 - 7 - 8+9+10+11+12 - 13 - 14 - 15 - 16....+1985+1986+1987+1988 - 1900 - 1991 - 1992+1993+1994+ - :: 1+2+3+4+(9+10+11+12-5-6-7-8)+(17+18+19+20-13-14-15-16)2001+2002+2003+2004-1997-1998-1999-20...1.计算下列各式的值: (2)11+12 - 13 - 14+15+16 - 17 - 18+…+99+10 - :: -1+3-5+7-9+11-…-1997+1999=(-1+3)+(-5+7)+(-9+11)+…+(-1997+1999)=2+2+2+……+2=2*500=1000 11+12-13-14+15+16-17-18+…+99+100=11+12+(-13-14+15+16)+(-17-18+19+20)+…+(-97-98+99+100)=11+12+4*22=111 1991*1999-1990*...
数学 11 - 12 - 13 - 14 - 15 - 16 - :: 11,312,113,39 4014,-b15,>016,>-2 =-2
(1)解方程:2xx - 2=1 - 12 - x;(2)计算:(1 - 12 - 13 - 14 - 15)(12+13+14+15+16) - (1 - 12 - 13 - 14 - 15 - 16)(12+13+14+15). - ::[答案] (1)去分母得:2x=x-2+1, 解得:x=-1, 经检验x=-1是分式方程的解; (2)设 1 2+ 1 3+ 1 4+ 1 5+ 1 6=a,原式=( 7 6-a)a-(1-a)(a- 1 6)= 7 6a-a2-a+ 1 6+a2- 1 6a= 1 6.
1+2+3+4 - 5 - 6 - 7 - 8+9+10+11+12 - 13 - 14 - 15 - 16·····+1993+ - :: 1+2+3+4−5−6−7−8+9+10+11+12−13−14−15−16+······+1993+1994+1995.分析:将数字分组,可知 3+4−5−6−7−8+9+10=0; 11+12−13−14−15−16+17+18=0; ······ (1995−2)÷8=249……1,得 1+2+3+4−5−6−7−8+9+10+11+12−13−14−15−16+······+1993+1994+1995=1+2+1995=1998
1 - 2 - 3+4+5 - 6 - 7+8+9 - 10 - 11+12+13 - 14 - 15+16= - :: 1-2-3+4+5-6-7+8+9-10-11+12+13-14-15+16=0 规律是从1开始 每四项相加为0
简算11 - 12 - 13 - 14 - 15 - 16 - 17 - 18 - 19 - 20 - :: 11-12-13-14-15-16-17-18-19-20 =11-(12+13+14+15+16+17+18+19+20) =11 -16x9 =11-144 =-133
12 - 4=13 - ( )=14 - ( )=15 - ( )=16 - ( ) 求解答 - :: 12-4=13-5=14-6=15-7=16-8
12 - 4=13 - ()=14 - ()=15 - ()=16 - ()谁能告诉我这道题 - :: 5、6、7、8
试计算1 - 12+13 - 14+15 - 16…+19?110= - :: 1-1 2 +1 3 -1 4 +1 5 -1 6 …+1 9 ?1 10 =1 2 +1 12 +1 30 +1 56 +1 90 =1260+210+84+45+28 2520 =1627 2520