数学题简算(分数)1/4*37+0.75*21(1/30+1/35+1/63)*2又1/718*6/7+6*1/7+16/7*61880*199又9/10-1999*187又9/1039*148/149+148*86/149+48*74/1492004除以2004又2004/200651又2/3*3/5+71又3/4*4/7+91又4/5*5/91998+1989*1987/1988*1989-11/1*2=1-1/2,1/2*3=1/2-1/3,1/3*4=1/3-1/4,1/4*5=()-(),1/5*6=()-().1/n*(n+1)()-();利用上面的规律计算:1/1*2+1/2*3+1/3*4+1/4*5+1/5*6+1/6*7说明道理+列式

问题描述:

数学题简算(分数)
1/4*37+0.75*21
(1/30+1/35+1/63)*2又1/7
18*6/7+6*1/7+16/7*6
1880*199又9/10-1999*187又9/10
39*148/149+148*86/149+48*74/149
2004除以2004又2004/2006
51又2/3*3/5+71又3/4*4/7+91又4/5*5/9
1998+1989*1987/1988*1989-1
1/1*2=1-1/2,1/2*3=1/2-1/3,1/3*4=1/3-1/4,1/4*5=()-(),1/5*6=()-().1/n*(n+1)()-();利用上面的规律计算:
1/1*2+1/2*3+1/3*4+1/4*5+1/5*6+1/6*7
说明道理+列式

1/4*37+0.75*21= 37/4 + 3/4 * 21= 37/4 + 21*3 /4= 37/4 + 63/4= 100/4= 25 (1/30+1/35+1/63)*2又1/7= (1/5*6 + 1/5*7 + 1/7*9 ) * 15/7= ( 1/5-1/6 + 2/5-2/7 + 2/7-2/9) * 15/7= ( 3/5 - 1/6 - 2/9 )* 15/7= (5...